diff --git a/components/email/__tests__/composer-offline-send.test.tsx b/components/email/__tests__/composer-offline-send.test.tsx
new file mode 100644
index 000000000..5c7b5f425
--- /dev/null
+++ b/components/email/__tests__/composer-offline-send.test.tsx
@@ -0,0 +1,289 @@
+import { act, fireEvent, render, screen, waitFor } from '@testing-library/react';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import React from 'react';
+import { EmailComposer } from '../email-composer';
+
+// Writing offline. The footer says "Offline" next to Send. With "Keep mail on
+// this device" on, Send puts the message in the outbox as before. Without it
+// nothing can keep the message safely for later: Send says so, keeps the
+// text, and points at the setting. It used to fail with "Failed to send".
+
+const offline = vi.hoisted(() => ({ active: false, allowed: true }));
+vi.mock('@/lib/offline/offline-mode', async (importOriginal) => ({
+  ...(await importOriginal<object>()),
+  offlineActive: () => offline.active,
+  offlineAllowed: () => offline.allowed,
+}));
+
+vi.mock('@/components/email/rich-text-editor', () => ({
+  RichTextEditor: ({ collapseToolbarOnMobile }: { collapseToolbarOnMobile?: boolean }) =>
+    React.createElement('div', { 'data-testid': 'rich-text-editor', 'data-collapsed': String(!!collapseToolbarOnMobile) }),
+}));
+
+vi.mock('@/components/plugins/plugin-slot', () => ({ PluginSlot: () => null }));
+vi.mock('@/components/ui/avatar', () => ({ Avatar: () => null }));
+vi.mock('@/components/identity/sub-address-helper', () => ({ SubAddressHelper: () => null }));
+vi.mock('@/components/templates/template-picker', () => ({ TemplatePicker: () => null }));
+vi.mock('@/components/templates/template-form', () => ({ TemplateForm: () => null }));
+vi.mock('@/components/files/file-preview-modal', () => ({ FilePreviewModal: () => null }));
+vi.mock('@/hooks/use-focus-trap', () => ({
+  useFocusTrap: () => ({ current: null }),
+}));
+vi.mock('@/hooks/use-pro-multi-account-identities', () => ({
+  useProMultiAccountIdentities: () => ({ enabled: false, groups: [], allIdentities: [] }),
+  stripCrossAccountIdentityPrefix: (id: string) => ({ localAccountId: null, rawId: id }),
+}));
+
+vi.mock('@/stores/auth-store', () => {
+  const state = {
+    client: null,
+    identities: [],
+    primaryIdentity: null,
+    isAuthenticated: false,
+    isDemoMode: false,
+    activeAccountId: null,
+    connectionLost: false,
+    getClientForAccount: () => undefined,
+    getAllConnectedClients: () => new Map(),
+    syncIdentities: () => {},
+    refreshIdentities: async () => {},
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useAuthStore: hook };
+});
+
+vi.mock('@/stores/identity-store', () => {
+  const state = {
+    identities: [{ id: 'id-me', email: 'me@example.com', name: 'Me' }],
+    defaultIdentityId: 'id-me',
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useIdentityStore: hook };
+});
+
+vi.mock('@/stores/account-store', () => {
+  const state = { accounts: [], getAccountById: () => undefined };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useAccountStore: hook };
+});
+
+vi.mock('@/stores/email-store', () => {
+  const state = {
+    draftSaveEnabled: false,
+    sendRawEmail: async () => ({ sent: true }),
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useEmailStore: hook };
+});
+
+vi.mock('@/stores/settings-store', () => {
+  const state = {
+    timeFormat: '24h',
+    plainTextMode: false,
+    subAddressDelimiter: '+',
+    autoSelectReplyIdentity: true,
+    attachmentReminderEnabled: false,
+    attachmentReminderKeywords: [],
+    emptySubjectWarningEnabled: true,
+    sendDelaySeconds: 0,
+    signaturePosition: 'above_quote',
+    signatureSeparatorEnabled: false,
+    requestReadReceiptDefault: false,
+    addTrustedSender: () => {},
+    trustedSendersAddressBook: null,
+    updateSetting: () => {},
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useSettingsStore: hook };
+});
+
+vi.mock('@/stores/contact-store', () => {
+  const state = {
+    contacts: [],
+    getAutocomplete: async () => [],
+    addToTrustedSendersBook: async () => {},
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useContactStore: hook };
+});
+
+vi.mock('@/stores/template-store', () => {
+  const state = { templates: [], addTemplate: async () => {} };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useTemplateStore: hook };
+});
+
+vi.mock('@/stores/toast-store', () => ({
+  toast: { info: () => {}, error: () => {}, success: () => {}, warning: () => {} },
+}));
+
+vi.mock('@/lib/plugin-hooks', () => ({
+  identityHooks: {
+    onSignatureRender: { size: 0, transform: async (value: unknown) => value },
+    onIdentitySelect: { size: 0, emit: async () => {} },
+  },
+  templateHooks: {
+    onTemplateRender: { size: 0, transform: async (value: unknown) => value },
+    onTemplateApply: { size: 0, emit: async () => {} },
+  },
+  emailHooks: {
+    onComposerOpen: { call: async () => [] },
+    onRecipientChange: { call: async () => [] },
+    getRecipientSuggestions: { call: async () => [] },
+    onRecipientChipsChange: { transform: async (chips: unknown) => chips },
+    onDraftChange: { emit: () => {} },
+    onBeforeDraftAutoSave: { transform: async (draft: unknown) => draft },
+    onBeforeEmailSend: { intercept: async () => true, interceptOutcome: async () => 'allowed' },
+    onComposeSend: { takeOver: async () => 'default' },
+    onTransformOutgoingEmail: { transform: async (email: unknown) => email },
+  },
+  contactHooks: {
+    search: { call: async () => [] },
+    onProvideRecipientSuggestions: { transform: async (initial: unknown) => initial },
+  },
+}));
+
+vi.mock('@/lib/email-sanitization', () => ({
+  sanitizeSignatureHtml: (v: string) => v,
+  sanitizeEmailHtml: (v: string) => v,
+  parseHtmlSafely: (html: string) => new DOMParser().parseFromString(html, 'text/html'),
+}));
+
+vi.mock('@/lib/email-threading', () => ({
+  computeReplyThreadingHeaders: () => ({ inReplyTo: [], references: [] }),
+}));
+vi.mock('@/lib/signature-utils', () => ({
+  appendPlainTextSignature: (body: string) => body,
+  getPlainTextSignature: () => '',
+}));
+vi.mock('@/lib/sub-addressing', () => ({ generateSubAddress: () => '' }));
+vi.mock('@/lib/debug', () => ({ debug: { log: () => {}, warn: () => {}, error: () => {} } }));
+vi.mock('@/components/email/quoted-html', () => ({
+  buildQuotedHtmlBlock: () => '',
+  serializeEditorContent: () => '',
+}));
+vi.mock('@/lib/template-utils', () => ({ substitutePlaceholders: (s: string) => s }));
+
+const DATA = {
+  to: 'bob@example.com',
+  cc: '',
+  bcc: '',
+  subject: 'Lunch',
+  body: '<p>Hello there</p>',
+  showCc: false,
+  showBcc: false,
+  selectedIdentityId: 'id-me',
+  subAddressTag: '',
+  mode: 'compose' as const,
+  draftId: null,
+};
+
+let online = true;
+beforeEach(() => {
+  online = true;
+  offline.active = false;
+  offline.allowed = true;
+  Object.defineProperty(navigator, 'onLine', { configurable: true, get: () => online });
+});
+afterEach(() => {
+  online = true;
+});
+
+function goOffline() {
+  online = false;
+  act(() => { window.dispatchEvent(new Event('offline')); });
+}
+function goOnline() {
+  online = true;
+  act(() => { window.dispatchEvent(new Event('online')); });
+}
+
+const footer = () => document.querySelector<HTMLElement>('[data-composer-footer]')!;
+
+describe('the composer while offline', () => {
+  it('says "Offline" next to Send, and stops once the network is back', () => {
+    render(<EmailComposer initialData={DATA} ownWindow={{}} />);
+    expect(screen.queryByTestId('composer-offline')).toBeNull();
+    goOffline();
+    const label = screen.getByTestId('composer-offline');
+    expect(footer()).toContainElement(label);
+    expect(label.textContent).toContain('offline');
+    expect(label.textContent).toContain('offline_hint');
+    goOnline();
+    expect(screen.queryByTestId('composer-offline')).toBeNull();
+  });
+
+  it('without offline mode, Send keeps the message and says why, with the way to the setting', async () => {
+    const onSend = vi.fn();
+    render(<EmailComposer initialData={DATA} ownWindow={{}} onSend={onSend} />);
+    goOffline();
+    fireEvent.click(screen.getByTestId('composer-send'));
+    const notice = await screen.findByTestId('composer-offline-notice');
+    expect(notice.textContent).toContain('offline_send_unsaved');
+    const link = screen.getByRole('link', { name: 'settings.keep_label' });
+    expect(link.getAttribute('href')).toMatch(/\/settings\/backup\/offline$/);
+    expect(link).toHaveAttribute('target', '_blank');
+    expect(onSend).not.toHaveBeenCalled();
+    expect(screen.getByTestId('email-composer')).toBeInTheDocument();
+
+    goOnline();
+    expect(screen.queryByTestId('composer-offline-notice')).toBeNull();
+  });
+
+  it('says the message is in Drafts only when the server has it', async () => {
+    render(<EmailComposer initialData={{ ...DATA, draftId: 'd1' }} ownWindow={{}} onSend={vi.fn()} />);
+    goOffline();
+    fireEvent.click(screen.getByTestId('composer-send'));
+    expect((await screen.findByTestId('composer-offline-notice')).textContent).toContain('offline_send_saved');
+  });
+
+  it('Ctrl+Enter takes the same way', async () => {
+    const onSend = vi.fn();
+    render(<EmailComposer initialData={DATA} ownWindow={{}} onSend={onSend} />);
+    goOffline();
+    fireEvent.keyDown(screen.getByTestId('composer-send'), { key: 'Enter', ctrlKey: true });
+    await screen.findByTestId('composer-offline-notice');
+    expect(onSend).not.toHaveBeenCalled();
+  });
+
+  it('leaves out the link where this device may not keep mail', async () => {
+    offline.allowed = false;
+    render(<EmailComposer initialData={DATA} ownWindow={{}} onSend={vi.fn()} />);
+    goOffline();
+    fireEvent.click(screen.getByTestId('composer-send'));
+    await screen.findByTestId('composer-offline-notice');
+    expect(screen.queryByRole('link', { name: 'settings.keep_label' })).toBeNull();
+  });
+
+  it('with offline mode on, Send goes ahead: the outbox keeps it until the network is back', async () => {
+    offline.active = true;
+    const onSend = vi.fn();
+    render(<EmailComposer initialData={DATA} ownWindow={{}} onSend={onSend} />);
+    goOffline();
+    expect(screen.getByTestId('composer-offline').textContent).toContain('offline_hint_outbox');
+    fireEvent.click(screen.getByTestId('composer-send'));
+    await waitFor(() => expect(onSend).toHaveBeenCalled());
+    expect(screen.queryByTestId('composer-offline-notice')).toBeNull();
+  });
+});
diff --git a/components/email/__tests__/composer-own-window.test.tsx b/components/email/__tests__/composer-own-window.test.tsx
index 199eee835..ab200fb56 100644
--- a/components/email/__tests__/composer-own-window.test.tsx
+++ b/components/email/__tests__/composer-own-window.test.tsx
@@ -1,5 +1,5 @@
 import React from 'react';
-import { cleanup, fireEvent, render, screen, waitFor } from '@testing-library/react';
+import { act, cleanup, fireEvent, render, screen, waitFor } from '@testing-library/react';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { NextIntlClientProvider } from 'next-intl';
 import { EmailComposer, type ComposerDraftData, type ComposerPopOut } from '../email-composer';
@@ -364,3 +364,22 @@ describe('a composer that is all its window shows', () => {
     expect(creations).toHaveLength(saved);
   });
 });
+
+describe('back online', () => {
+  it('saves what could not be saved while offline, so "saved in Drafts once you are back online" holds', async () => {
+    let onLine = true;
+    vi.spyOn(navigator, 'onLine', 'get').mockImplementation(() => onLine);
+    rejectSave = true;
+    mount({});
+    onLine = false;
+    act(() => { window.dispatchEvent(new Event('offline')); });
+    fireEvent.change(subjectField(), { target: { value: 'Written on a train' } });
+    await waitFor(() => expect(creations).toHaveLength(1), { timeout: 4000 });
+
+    rejectSave = false;
+    onLine = true;
+    act(() => { window.dispatchEvent(new Event('online')); });
+    await waitFor(() => expect(creations).toHaveLength(2));
+    expect(creations[1].subject).toBe('Written on a train');
+  });
+});
diff --git a/components/email/__tests__/composer-windows-layout.test.tsx b/components/email/__tests__/composer-windows-layout.test.tsx
new file mode 100644
index 000000000..a5a5dd5a4
--- /dev/null
+++ b/components/email/__tests__/composer-windows-layout.test.tsx
@@ -0,0 +1,275 @@
+import { fireEvent, render, screen, within } from '@testing-library/react';
+import { describe, it, expect, vi } from 'vitest';
+import React from 'react';
+import { EmailComposer } from '../email-composer';
+
+// One layout in every composer: Send at the bottom end, Discard as a bin left
+// of it, the formatting toolbar showing. A pop-out or quick compose window is
+// narrower than a tablet, and used to get the phone's layout: Send in the
+// header, Discard where Send was, the toolbar behind a button.
+
+vi.mock('@/components/email/rich-text-editor', () => ({
+  RichTextEditor: ({ collapseToolbarOnMobile }: { collapseToolbarOnMobile?: boolean }) =>
+    React.createElement('div', { 'data-testid': 'rich-text-editor', 'data-collapsed': String(!!collapseToolbarOnMobile) }),
+}));
+
+vi.mock('@/components/plugins/plugin-slot', () => ({ PluginSlot: () => null }));
+vi.mock('@/components/ui/avatar', () => ({ Avatar: () => null }));
+vi.mock('@/components/identity/sub-address-helper', () => ({ SubAddressHelper: () => null }));
+vi.mock('@/components/templates/template-picker', () => ({ TemplatePicker: () => null }));
+vi.mock('@/components/templates/template-form', () => ({ TemplateForm: () => null }));
+vi.mock('@/components/files/file-preview-modal', () => ({ FilePreviewModal: () => null }));
+vi.mock('@/hooks/use-focus-trap', () => ({
+  useFocusTrap: () => ({ current: null }),
+}));
+vi.mock('@/hooks/use-pro-multi-account-identities', () => ({
+  useProMultiAccountIdentities: () => ({ enabled: false, groups: [], allIdentities: [] }),
+  stripCrossAccountIdentityPrefix: (id: string) => ({ localAccountId: null, rawId: id }),
+}));
+
+vi.mock('@/stores/auth-store', () => {
+  const state = {
+    client: null,
+    identities: [],
+    primaryIdentity: null,
+    isAuthenticated: false,
+    isDemoMode: false,
+    activeAccountId: null,
+    connectionLost: false,
+    getClientForAccount: () => undefined,
+    getAllConnectedClients: () => new Map(),
+    syncIdentities: () => {},
+    refreshIdentities: async () => {},
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useAuthStore: hook };
+});
+
+vi.mock('@/stores/identity-store', () => {
+  const state = {
+    identities: [{ id: 'id-me', email: 'me@example.com', name: 'Me' }],
+    defaultIdentityId: 'id-me',
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useIdentityStore: hook };
+});
+
+vi.mock('@/stores/account-store', () => {
+  const state = { accounts: [], getAccountById: () => undefined };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useAccountStore: hook };
+});
+
+vi.mock('@/stores/email-store', () => {
+  const state = {
+    draftSaveEnabled: false,
+    sendRawEmail: async () => ({ sent: true }),
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useEmailStore: hook };
+});
+
+vi.mock('@/stores/settings-store', () => {
+  const state = {
+    timeFormat: '24h',
+    plainTextMode: false,
+    subAddressDelimiter: '+',
+    autoSelectReplyIdentity: true,
+    attachmentReminderEnabled: false,
+    attachmentReminderKeywords: [],
+    emptySubjectWarningEnabled: true,
+    sendDelaySeconds: 0,
+    signaturePosition: 'above_quote',
+    signatureSeparatorEnabled: false,
+    requestReadReceiptDefault: false,
+    addTrustedSender: () => {},
+    trustedSendersAddressBook: null,
+    updateSetting: () => {},
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useSettingsStore: hook };
+});
+
+vi.mock('@/stores/contact-store', () => {
+  const state = {
+    contacts: [],
+    getAutocomplete: async () => [],
+    addToTrustedSendersBook: async () => {},
+  };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useContactStore: hook };
+});
+
+vi.mock('@/stores/template-store', () => {
+  const state = { templates: [], addTemplate: async () => {} };
+  const hook = (sel?: (s: typeof state) => unknown) =>
+    typeof sel === 'function' ? sel(state) : state;
+  hook.getState = () => state;
+  hook.setState = (p: Partial<typeof state>) => Object.assign(state, p);
+  return { useTemplateStore: hook };
+});
+
+vi.mock('@/stores/toast-store', () => ({
+  toast: { info: () => {}, error: () => {}, success: () => {}, warning: () => {} },
+}));
+
+vi.mock('@/lib/plugin-hooks', () => ({
+  identityHooks: {
+    onSignatureRender: { size: 0, transform: async (value: unknown) => value },
+    onIdentitySelect: { size: 0, emit: async () => {} },
+  },
+  templateHooks: {
+    onTemplateRender: { size: 0, transform: async (value: unknown) => value },
+    onTemplateApply: { size: 0, emit: async () => {} },
+  },
+  emailHooks: {
+    onComposerOpen: { call: async () => [] },
+    onRecipientChange: { call: async () => [] },
+    getRecipientSuggestions: { call: async () => [] },
+    onRecipientChipsChange: { transform: async (chips: unknown) => chips },
+    onDraftChange: { emit: () => {} },
+    onBeforeDraftAutoSave: { transform: async (draft: unknown) => draft },
+    onBeforeEmailSend: { intercept: async () => true, interceptOutcome: async () => 'allowed' },
+    onComposeSend: { takeOver: async () => 'default' },
+    onTransformOutgoingEmail: { transform: async (email: unknown) => email },
+  },
+  contactHooks: {
+    search: { call: async () => [] },
+    onProvideRecipientSuggestions: { transform: async (initial: unknown) => initial },
+  },
+}));
+
+vi.mock('@/lib/email-sanitization', () => ({
+  sanitizeSignatureHtml: (v: string) => v,
+  sanitizeEmailHtml: (v: string) => v,
+  parseHtmlSafely: (html: string) => new DOMParser().parseFromString(html, 'text/html'),
+}));
+
+vi.mock('@/lib/email-threading', () => ({
+  computeReplyThreadingHeaders: () => ({ inReplyTo: [], references: [] }),
+}));
+vi.mock('@/lib/signature-utils', () => ({
+  appendPlainTextSignature: (body: string) => body,
+  getPlainTextSignature: () => '',
+}));
+vi.mock('@/lib/sub-addressing', () => ({ generateSubAddress: () => '' }));
+vi.mock('@/lib/debug', () => ({ debug: { log: () => {}, warn: () => {}, error: () => {} } }));
+vi.mock('@/components/email/quoted-html', () => ({
+  buildQuotedHtmlBlock: () => '',
+  serializeEditorContent: () => '',
+}));
+vi.mock('@/lib/template-utils', () => ({ substitutePlaceholders: (s: string) => s }));
+
+const DATA = {
+  to: 'bob@example.com',
+  cc: '',
+  bcc: '',
+  subject: 'Lunch',
+  body: '<p>Hello there</p>',
+  showCc: false,
+  showBcc: false,
+  selectedIdentityId: 'id-me',
+  subAddressTag: '',
+  mode: 'compose' as const,
+  draftId: null,
+};
+
+const footer = () => document.querySelector<HTMLElement>('[data-composer-footer]')!;
+const header = () => document.querySelector<HTMLElement>('[data-composer-header]')!;
+
+describe('a composer in a window of its own', () => {
+  it('has one Send, at the bottom end, with Discard as a bin right before it', () => {
+    render(<EmailComposer initialData={DATA} ownWindow={{}} />);
+    const sends = screen.getAllByTestId('composer-send');
+    expect(sends).toHaveLength(1);
+    expect(footer()).toContainElement(sends[0]);
+    expect(sends[0].className).not.toMatch(/(^|\s)hidden(\s|$)/);
+    expect(within(header()).queryByTestId('composer-send')).toBeNull();
+
+    const discard = screen.getByTestId('composer-discard');
+    expect(discard.querySelector('svg')).not.toBeNull();
+    // Right before Send, in the same group.
+    expect(discard.nextElementSibling).toBe(sends[0]);
+  });
+
+  it('shows the formatting toolbar, with no button to fold it away', () => {
+    render(<EmailComposer initialData={DATA} ownWindow={{}} />);
+    expect(screen.getByTestId('rich-text-editor')).toHaveAttribute('data-collapsed', 'false');
+    expect(screen.queryByRole('button', { name: 'formatting' })).toBeNull();
+  });
+
+  it('keeps the close button where the main window has it', () => {
+    render(<EmailComposer initialData={DATA} ownWindow={{}} />);
+    expect(screen.getByTestId('composer-close').className).not.toContain('order-first');
+  });
+});
+
+describe('full screen', () => {
+  it('puts the composer over the whole window, and the same button puts it back', () => {
+    render(<EmailComposer initialData={DATA} />);
+    const root = screen.getByTestId('email-composer');
+    expect(root).not.toHaveAttribute('data-maximized');
+
+    fireEvent.click(screen.getByRole('button', { name: 'maximize' }));
+    expect(root).toHaveAttribute('data-maximized');
+    expect(root.className).toMatch(/(^|\s)fixed(\s|$)/);
+    expect(root.className).toContain('inset-0');
+
+    fireEvent.click(screen.getByRole('button', { name: 'restore' }));
+    expect(root).not.toHaveAttribute('data-maximized');
+    expect(root.className).not.toMatch(/(^|\s)fixed(\s|$)/);
+  });
+
+  it('goes back with Escape, without closing the composer', () => {
+    const onClose = vi.fn();
+    render(<EmailComposer initialData={DATA} onClose={onClose} />);
+    fireEvent.click(screen.getByRole('button', { name: 'maximize' }));
+    const root = screen.getByTestId('email-composer');
+
+    fireEvent.keyDown(screen.getByRole('button', { name: 'restore' }), { key: 'Escape' });
+
+    expect(root).not.toHaveAttribute('data-maximized');
+    expect(onClose).not.toHaveBeenCalled();
+    expect(screen.queryByRole('alertdialog')).toBeNull();
+  });
+
+  it('is not offered in a window of its own, which is all composer already', () => {
+    render(<EmailComposer initialData={DATA} ownWindow={{}} />);
+    expect(screen.queryByRole('button', { name: 'maximize' })).toBeNull();
+  });
+});
+
+describe('a composer in the main window', () => {
+  it('keeps the phone layout for a phone: Send in the header there, toolbar folded', () => {
+    render(<EmailComposer initialData={DATA} />);
+    expect(within(header()).getByTestId('composer-send')).toBeInTheDocument();
+    expect(screen.getByTestId('rich-text-editor')).toHaveAttribute('data-collapsed', 'true');
+    expect(screen.getByRole('button', { name: 'formatting' })).toBeInTheDocument();
+  });
+
+  it('shows Discard as a bin too, with its name for screen readers', () => {
+    render(<EmailComposer initialData={DATA} />);
+    const discard = screen.getByTestId('composer-discard');
+    expect(discard).toHaveAccessibleName('discard');
+    expect(discard.querySelector('svg')).not.toBeNull();
+    expect(within(discard).getByText('discard').className).toContain('sr-only');
+  });
+});
diff --git a/components/email/__tests__/rich-text-editor-toolbar-overflow.test.tsx b/components/email/__tests__/rich-text-editor-toolbar-overflow.test.tsx
new file mode 100644
index 000000000..c45bc217c
--- /dev/null
+++ b/components/email/__tests__/rich-text-editor-toolbar-overflow.test.tsx
@@ -0,0 +1,114 @@
+import { act, fireEvent, render, screen, waitFor, within } from '@testing-library/react';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import React from 'react';
+
+import { RichTextEditor, formattingFoldCount } from '../rich-text-editor';
+
+// The formatting toolbar keeps one row: in a narrow composer (585 px at
+// 1280x720) it wrapped to two and took the body's room. What doesn't fit goes
+// behind "More formatting", the least used first.
+
+let toolbarWidth = 1200;
+const observers = new Set<ResizeObserverCallback>();
+class ReportingResizeObserver {
+  constructor(private cb: ResizeObserverCallback) {}
+  observe() { observers.add(this.cb); }
+  unobserve() {}
+  disconnect() { observers.delete(this.cb); }
+}
+vi.stubGlobal('ResizeObserver', ReportingResizeObserver);
+
+const realClientWidth = Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'clientWidth')!;
+Object.defineProperty(HTMLElement.prototype, 'clientWidth', {
+  configurable: true,
+  get(this: HTMLElement) {
+    return this.getAttribute('role') === 'toolbar' ? toolbarWidth : realClientWidth.get!.call(this);
+  },
+});
+
+afterEach(() => {
+  toolbarWidth = 1200;
+});
+
+async function setup() {
+  let ready = false;
+  render(<RichTextEditor content="<p>Hello</p>" onChange={() => {}} onEditorReady={() => { ready = true; }} />);
+  await waitFor(() => expect(ready).toBe(true));
+}
+
+async function resize(width: number) {
+  toolbarWidth = width;
+  await act(async () => {
+    for (const cb of observers) cb([], {} as ResizeObserver);
+  });
+}
+
+const toolbar = () => screen.getByRole('toolbar', { name: 'formatting' });
+const rowItem = (name: string) => toolbar().querySelector(`[data-toolbar-item="${name}"]`);
+
+describe('formatting toolbar in a narrow composer', () => {
+  it('shows every button in one row when there is room, without a More button', async () => {
+    await setup();
+    for (const name of ['heading-1', 'quote', 'align-left', 'table', 'undo']) expect(rowItem(name)).not.toBeNull();
+    expect(rowItem('more-formatting')).toBeNull();
+  });
+
+  it('moves what does not fit behind "More formatting", and shows it there', async () => {
+    await setup();
+    await resize(561);
+
+    // The least used go first: undo, redo, clear formatting, then alignment.
+    for (const name of ['undo', 'redo', 'clear-formatting', 'align-left', 'align-right']) expect(rowItem(name)).toBeNull();
+    for (const name of ['bold', 'bullet-list', 'link', 'heading-1', 'table']) expect(rowItem(name)).not.toBeNull();
+
+    const more = rowItem('more-formatting') as HTMLButtonElement;
+    expect(more).toHaveAccessibleName('more_formatting');
+    expect(more).toHaveAttribute('aria-expanded', 'false');
+    fireEvent.click(more);
+    const panel = screen.getByRole('dialog', { name: 'more_formatting' });
+    expect(more).toHaveAttribute('aria-expanded', 'true');
+    for (const name of ['align-left', 'align-center', 'align-right', 'clear-formatting', 'undo', 'redo']) {
+      expect(within(panel).getByRole('button', { name: new RegExp(`^${name.replace('-', '_')}`) })).toBeInTheDocument();
+    }
+  });
+
+  it('keeps the arrows in the row: the panel buttons are no Tab stops of the toolbar', async () => {
+    await setup();
+    await resize(561);
+    fireEvent.click(rowItem('more-formatting')!);
+    const panel = screen.getByRole('dialog', { name: 'more_formatting' });
+    const rowStops = Array.from(toolbar().querySelectorAll<HTMLElement>('[data-toolbar-item]'))
+      .filter((el) => !panel.contains(el) && el.tabIndex === 0);
+    expect(rowStops).toHaveLength(1);
+  });
+
+  it('brings everything back into the row when the composer gets wider', async () => {
+    await setup();
+    await resize(400);
+    expect(rowItem('heading-1')).toBeNull();
+    await resize(1000);
+    expect(rowItem('heading-1')).not.toBeNull();
+    expect(rowItem('undo')).not.toBeNull();
+    expect(rowItem('more-formatting')).toBeNull();
+  });
+});
+
+describe('formattingFoldCount', () => {
+  const sizes = { button: 28, gap: 2, separator: 5 };
+
+  it('folds nothing for a toolbar that is not laid out', () => {
+    expect(formattingFoldCount(0, sizes)).toBe(0);
+  });
+
+  it('folds more groups the narrower the row', () => {
+    const counts = [900, 700, 561, 480, 400, 300].map((width) => formattingFoldCount(width, sizes));
+    expect(counts[0]).toBe(0);
+    for (let i = 1; i < counts.length; i++) expect(counts[i]).toBeGreaterThanOrEqual(counts[i - 1]);
+    expect(counts[counts.length - 1]).toBe(5);
+  });
+
+  it('makes room for the text direction button', () => {
+    const width = 700;
+    expect(formattingFoldCount(width, { ...sizes, directionButton: true })).toBeGreaterThanOrEqual(formattingFoldCount(width, sizes));
+  });
+});
diff --git a/components/email/email-composer.tsx b/components/email/email-composer.tsx
index c93e6c7b9..ef1a8a99d 100644
--- a/components/email/email-composer.tsx
+++ b/components/email/email-composer.tsx
@@ -42,6 +42,7 @@ import {
   Forward,
   BookUser,
   Lock,
+  CloudOff,
 } from "@/components/icons";
 import { useRouter } from "@/i18n/navigation";
 import { ComposerPluginMenuItems, ComposerPluginToolbarButtons, ComposerToolbarMenu, ComposerToolbarMenuItem, ComposerToolbarMenuCheckItem } from "@/components/email/composer-toolbar-menu";
@@ -100,6 +101,9 @@ import type { DirectoryEntry } from "@/stores/contact-store";
 import type { IJMAPClient } from "@/lib/jmap/client-interface";
 import { isStandInId } from "@/lib/jmap/stand-in-ids";
 import { noteDraftReplacedElsewhere } from "@/lib/offline/queue";
+import { offlineActive, offlineAllowed } from "@/lib/offline/offline-mode";
+import { useBrowserOnline } from "@/hooks/use-browser-online";
+import { appPath, buildSettingsPath } from "@/lib/deep-links";
 import type { FileNode } from "@/lib/jmap/types";
 import { useContactStore, getContactDisplayName, getContactPrimaryEmail } from "@/stores/contact-store";
 import { renderTemplateWithPlugins, notifyTemplateApplied } from "@/stores/template-store";
@@ -1215,6 +1219,13 @@ export function EmailComposer({
   // bar folded away behind "Aa" until asked for.
   const mvWindow = useMvComposeWindow();
   const [mvShowFormatting, setMvShowFormatting] = useState(false);
+  // A pop-out or quick compose window is narrower than a tablet, but it is a
+  // window on a computer: it keeps the main window's layout, not the phone's.
+  const phoneLayout = !ownWindow;
+  // Full screen: the composer over the whole window, as Gmail has it. The same
+  // button or Escape puts it back. Not in a window of its own, which is all composer.
+  const [maximized, setMaximized] = useState(false);
+  const canMaximize = !ownWindow && !mvWindow;
   // "close" (X, Escape): save or discard. "discard" (the Discard button): the
   // user already chose, so only confirm it.
   const [closeDialogKind, setCloseDialogKind] = useState<'close' | 'discard'>('close');
@@ -4654,6 +4665,35 @@ export function EmailComposer({
     };
   });
 
+  // Offline. With "Keep mail on this device" on, a send waits in the outbox
+  // and goes out once the server answers again. Without it there is nowhere
+  // safe to keep a message for later: Send says so and the text stays here.
+  const tComposeWindows = useTranslations('compose_windows');
+  const browserOnline = useBrowserOnline();
+  const [offlineSendNotice, setOfflineSendNotice] = useState<'saved' | 'unsaved' | null>(null);
+  const sendOrSayOffline = () => {
+    if (typeof navigator !== 'undefined' && navigator.onLine === false && !offlineActive(composingAccountId ?? null)) {
+      const saved = !!draftIdRef.current && changeVersionRef.current === savedVersionRef.current && !saveFailedRef.current;
+      setOfflineSendNotice(saved ? 'saved' : 'unsaved');
+      announceStatus(tComposeWindows(saved ? 'offline_send_saved' : 'offline_send_unsaved'));
+      return;
+    }
+    handleSend();
+  };
+  // Back online: the notice goes, and what couldn't be saved meanwhile is saved now.
+  const wasOnlineRef = useRef(browserOnline);
+  useEffect(() => {
+    const cameBack = browserOnline && !wasOnlineRef.current;
+    wasOnlineRef.current = browserOnline;
+    if (!cameBack) return;
+    setOfflineSendNotice(null);
+    if (saveCloseAttemptRef.current || sentRef.current || isSendingRef.current || !isDirtyRef.current) return;
+    if (changeVersionRef.current === savedVersionRef.current && !saveFailedRef.current) return;
+    void saveDraftRef.current({ auto: true });
+  }, [browserOnline]);
+  // Only asked while offline: it reads the organisation's policy and the store's support.
+  const offlineHint = browserOnline ? '' : tComposeWindows(offlineActive(composingAccountId ?? null) ? 'offline_hint_outbox' : 'offline_hint');
+
   const handleComposerKeyDown = (e: React.KeyboardEvent<HTMLDivElement>) => {
     if (e.defaultPrevented) return;
     // Keys from a dialog the composer opened (Insert link, ...) reach here
@@ -4698,6 +4738,11 @@ export function EmailComposer({
       // And for proofreading's popup and panel: Escape closes only them.
       if (proofreading.popup || proofreading.panel) return;
       e.preventDefault();
+      // Full screen first goes back to where the composer was.
+      if (maximized) {
+        setMaximized(false);
+        return;
+      }
       handleClose();
       return;
     }
@@ -4715,7 +4760,7 @@ export function EmailComposer({
       }
 
       e.preventDefault();
-      handleSend();
+      sendOrSayOffline();
       return;
     }
 
@@ -4731,7 +4776,13 @@ export function EmailComposer({
       data-testid="email-composer"
       // Edits made while the draft moves wouldn't move with it.
       inert={isPoppingOut || undefined}
-      className={cn("flex h-full bg-background relative", className)}
+      className={cn(
+        "flex h-full bg-background relative",
+        className,
+        // Over everything but dialogs (z-60) and toasts; below the desktop app's window controls.
+        maximized && "fixed inset-0 z-40 h-auto pt-[var(--titlebar-row-height)]",
+      )}
+      data-maximized={maximized || undefined}
       onKeyDownCapture={handleComposerKeyDown}
       // Bubble phase, in the same batch as the field's own onChange. A state
       // change in the capture phase renders first and puts the old value back.
@@ -4858,28 +4909,28 @@ export function EmailComposer({
             {saveStatus === 'saving' && (
               <div className="flex items-center gap-1 text-xs text-muted-foreground">
                 <Save className="w-3 h-3 animate-pulse" />
-                <span className="hidden md:inline">{t('saving')}</span>
+                <span className={phoneLayout ? "hidden md:inline" : undefined}>{t('saving')}</span>
               </div>
             )}
             {saveStatus === 'saved' && (
               <div className="flex items-center gap-1 text-xs text-emerald-600 dark:text-emerald-400">
                 <Check className="w-3 h-3" />
-                <span className="hidden md:inline">{savedOnDevice ? tOfflineDrafts('saved_on_device') : t('draft_saved')}</span>
+                <span className={phoneLayout ? "hidden md:inline" : undefined}>{savedOnDevice ? tOfflineDrafts('saved_on_device') : t('draft_saved')}</span>
               </div>
             )}
             {saveStatus === 'error' && (
               <div className="flex items-center gap-1 text-xs text-red-600 dark:text-red-400">
                 <X className="w-3 h-3" />
-                <span className="hidden md:inline">{t('save_failed')}</span>
+                <span className={phoneLayout ? "hidden md:inline" : undefined}>{t('save_failed')}</span>
               </div>
             )}
           </div>
         </div>
         {/* Mobile: keep scheduled send reachable without consuming footer space. */}
-        {composerClient?.hasDelayedSend() || hasSendMenuActions ? (
+        {phoneLayout && (composerClient?.hasDelayedSend() || hasSendMenuActions ? (
           <div className="relative inline-flex md:hidden">
             <Button
-              onClick={() => handleSend()}
+              onClick={() => sendOrSayOffline()}
               disabled={!canSend || isSending || isSavingAndClosing}
               title={getSendTooltip()}
               size="sm"
@@ -4906,7 +4957,7 @@ export function EmailComposer({
           </div>
         ) : (
           <Button
-            onClick={() => handleSend()}
+            onClick={() => sendOrSayOffline()}
             disabled={!canSend || isSending || isSavingAndClosing}
             title={getSendTooltip()}
             size="sm"
@@ -4916,14 +4967,26 @@ export function EmailComposer({
             <Send className="w-4 h-4 me-1.5" />
             {t('send')}
           </Button>
-        )}
+        ))}
         {rightPanelToggle}
-        {popOutButton("hidden md:grid h-8 w-8 place-items-center rounded-md text-muted-foreground hover:bg-muted hover:text-foreground", "w-4 h-4")}
+        {canMaximize && (
+          <button
+            type="button"
+            onClick={() => setMaximized((v) => !v)}
+            className="hidden md:grid h-8 w-8 place-items-center rounded-md text-muted-foreground hover:bg-muted hover:text-foreground"
+            aria-label={maximized ? t('restore') : t('maximize')}
+            title={maximized ? t('restore') : t('maximize')}
+            data-testid="composer-maximize"
+          >
+            {maximized ? <Minimize2 className="w-4 h-4" /> : <Maximize2 className="w-4 h-4" />}
+          </button>
+        )}
+        {popOutButton(cn(phoneLayout ? "hidden md:grid" : "grid", "h-8 w-8 place-items-center rounded-md text-muted-foreground hover:bg-muted hover:text-foreground"), "w-4 h-4")}
         {/* Close at the top end (R4). On a phone it moves to the start, as
             the phone's mail apps have it, with Send at the end. */}
         <IconButton
           onClick={() => handleClose()}
-          className="-me-2 max-md:order-first max-md:me-0 max-md:-ms-2 max-md:h-11 max-md:w-11"
+          className={phoneLayout ? "-me-2 max-md:order-first max-md:me-0 max-md:-ms-2 max-md:h-11 max-md:w-11" : "-me-2"}
           label={tCommon('close')}
           data-testid="composer-close"
           data-own-window-close={ownWindow ? "" : undefined}
@@ -5333,7 +5396,7 @@ export function EmailComposer({
               ariaInvalid={validationErrors.body}
               ariaDescribedBy={`${fieldIdBase}-body-error`}
               defaultTextStyle={composeStyle}
-              collapseToolbarOnMobile={!showFormattingOnMobile}
+              collapseToolbarOnMobile={phoneLayout && !showFormattingOnMobile}
               toolbarPlacement={mvWindow ? (mvShowFormatting ? 'bottom' : 'hidden') : 'top'}
               onEditorReady={handleEditorReady}
               mentionCandidates={recipientMentionsEnabled ? mentionCandidates : undefined}
@@ -5544,6 +5607,23 @@ export function EmailComposer({
           </div>
         )}
 
+        {offlineSendNotice && !browserOnline && (
+          <div className="flex flex-wrap items-center gap-x-3 gap-y-1 border-t bg-muted px-4 py-2 text-sm text-foreground" data-testid="composer-offline-notice">
+            <CloudOff className="h-4 w-4 shrink-0" aria-hidden="true" />
+            <span className="min-w-0">{tComposeWindows(offlineSendNotice === 'saved' ? 'offline_send_saved' : 'offline_send_unsaved')}</span>
+            {offlineAllowed(composingAccountId ?? null) && (
+              <a
+                href={appPath(buildSettingsPath('backup', 'offline'))}
+                target="_blank"
+                rel="noopener"
+                className="font-medium text-primary underline underline-offset-2"
+              >
+                {tOffline('settings.keep_label')}
+              </a>
+            )}
+          </div>
+        )}
+
         {/* Bottom toolbar. In Mountain View's window both halves fold into
             one row (see [data-mv-compose-footer] in globals.css): Send first,
             the tools after it, and Discard as a bin at the far end. */}
@@ -5598,7 +5678,7 @@ export function EmailComposer({
                 <span className="hidden @[40rem]/composer-bar:inline text-sm">{t('attach')}</span>
               </Button>
             )}
-            {!plainTextMode && (
+            {!plainTextMode && (mvWindow || phoneLayout) && (
               <Button
                 variant="ghost"
                 size="icon"
@@ -5732,6 +5812,13 @@ export function EmailComposer({
 
           {/* Right side - Discard + Send (desktop) */}
           <div className="flex shrink-0 items-center gap-2">
+            {!browserOnline && (
+              <span className="flex items-center gap-1 text-xs text-muted-foreground" title={offlineHint} data-testid="composer-offline">
+                <CloudOff className="h-3.5 w-3.5" aria-hidden="true" />
+                {tComposeWindows('offline')}
+                <span className="sr-only">{offlineHint}</span>
+              </span>
+            )}
             {mvWindow ? (
               <button
                 type="button"
@@ -5752,17 +5839,17 @@ export function EmailComposer({
                 data-testid="composer-discard"
                 aria-label={t('discard')}
                 title={t('discard')}
-                className="text-muted-foreground hover:text-destructive hover:bg-destructive/10 md:@max-[26rem]/composer-bar:px-2.5 max-md:@max-[23rem]/composer-bar:px-2.5"
+                className="px-2.5 text-muted-foreground hover:text-destructive hover:bg-destructive/10 max-md:h-11 max-md:w-11"
               >
-                {/* Next to Send in a narrow composer the word runs over the tools on the left. */}
-                <Trash2 className="hidden w-4 h-4 max-md:@max-[23rem]/composer-bar:block md:block md:@[26rem]/composer-bar:hidden" aria-hidden="true" />
-                <span className="max-md:@max-[23rem]/composer-bar:hidden md:hidden md:@[26rem]/composer-bar:inline">{t('discard')}</span>
+                {/* A bin left of Send in every composer: the word ran over the tools in a narrow one. */}
+                <Trash2 className="w-4 h-4" aria-hidden="true" />
+                <span className="sr-only">{t('discard')}</span>
               </Button>
             )}
             {composerClient?.hasDelayedSend() || hasSendMenuActions ? (
-              <div data-mv-send={mvWindow ? "" : undefined} className="relative hidden md:inline-flex">
+              <div data-mv-send={mvWindow ? "" : undefined} className={cn("relative", phoneLayout ? "hidden md:inline-flex" : "inline-flex")}>
                 <Button
-                  onClick={() => handleSend()}
+                  onClick={() => sendOrSayOffline()}
                   disabled={!canSend || isSending || isSavingAndClosing}
                   title={getSendTooltip()}
                   data-testid="composer-send"
@@ -5787,12 +5874,12 @@ export function EmailComposer({
               </div>
             ) : (
               <Button
-                onClick={() => handleSend()}
+                onClick={() => sendOrSayOffline()}
                 disabled={!canSend || isSending || isSavingAndClosing}
                 title={getSendTooltip()}
                 data-testid="composer-send"
                 data-mv-send={mvWindow ? "" : undefined}
-                className="hidden md:inline-flex"
+                className={phoneLayout ? "hidden md:inline-flex" : "inline-flex"}
               >
                 <Send className="w-4 h-4 me-2" />
                 {t('send')}
diff --git a/components/email/rich-text-editor.tsx b/components/email/rich-text-editor.tsx
index 3448897cd..d4e4ac6cd 100644
--- a/components/email/rich-text-editor.tsx
+++ b/components/email/rich-text-editor.tsx
@@ -70,8 +70,56 @@ import {
   Rows3,
   Columns3,
   ImageIcon,
+  Ellipsis,
 } from "@/components/icons";
 
+/**
+ * Groups of the formatting toolbar that move behind "More formatting" when one
+ * row is too narrow for all of them, the least used first. Each with its
+ * buttons and the separators that go with it.
+ */
+const FOLDABLE_GROUPS = [
+  { id: "history", buttons: 3, separators: 2 },
+  { id: "align", buttons: 3, separators: 1 },
+  { id: "headings", buttons: 2, separators: 1 },
+  { id: "table", buttons: 1, separators: 0 },
+  { id: "blocks", buttons: 2, separators: 0 },
+] as const;
+type FoldableGroup = (typeof FOLDABLE_GROUPS)[number]["id"];
+/**
+ * Always in the row: font size, bold, italic, underline, strikethrough, the
+ * two colours, the lists, link, an image's description and More (12), with
+ * their 3 separators.
+ */
+const FIXED_TOOLBAR = { buttons: 12, separators: 3 };
+
+/**
+ * How many of FOLDABLE_GROUPS go behind "More formatting" for one row of
+ * `width` px. 0 for a toolbar that isn't laid out (hidden, or not measured).
+ */
+export function formattingFoldCount(width: number, sizes: { button: number; gap: number; separator: number; directionButton?: boolean }): number {
+  if (!(width > 0)) return 0;
+  const span = (buttons: number, separators: number) => buttons * (sizes.button + sizes.gap) + separators * (sizes.separator + sizes.gap);
+  const groups = FOLDABLE_GROUPS.map((group) => span(group.buttons + (group.id === "align" && sizes.directionButton ? 1 : 0), group.separators));
+  let needed = span(FIXED_TOOLBAR.buttons, FIXED_TOOLBAR.separators) + groups.reduce((sum, group) => sum + group, 0);
+  // All of it fits without the More button.
+  if (needed - (sizes.button + sizes.gap) <= width + 1) return 0;
+  for (let count = 1; count <= groups.length; count++) {
+    needed -= groups[count - 1];
+    if (needed <= width + 1) return count;
+  }
+  return groups.length;
+}
+
+/** The toolbar's inner width and the sizes of what is in it, in px. */
+function measureFormattingToolbar(toolbar: HTMLElement, directionButton: boolean): number {
+  const rem = parseFloat(getComputedStyle(document.documentElement).fontSize) || 16;
+  const style = getComputedStyle(toolbar);
+  const width = toolbar.clientWidth - (parseFloat(style.paddingLeft) || 0) - (parseFloat(style.paddingRight) || 0);
+  const button = toolbar.querySelector<HTMLElement>(":scope > [data-toolbar-item], :scope > div > [data-toolbar-item]")?.offsetWidth || 1.75 * rem;
+  return formattingFoldCount(width, { button, gap: 0.125 * rem, separator: 1 + 0.25 * rem, directionButton });
+}
+
 export interface InlineImageUpload {
   src: string;
   cid?: string;
@@ -699,6 +747,7 @@ export function RichTextEditor({
   }, [editor, linkDialog]);
 
   const tToolbar = useTranslations("email_composer.toolbar");
+  const tWindows = useTranslations("compose_windows");
   const tCommon = useTranslations("common");
   const [tableMenuOpen, setTableMenuOpen] = useState(false);
   const tableWrapperRef = useRef<HTMLDivElement>(null);
@@ -717,11 +766,13 @@ export function RichTextEditor({
   // focus last keeps it, the arrows, Home and End move inside.
   const toolbarRef = useRef<HTMLDivElement>(null);
   const rovingItemRef = useRef<string | null>(null);
+  // Buttons in the "More formatting" panel are the panel's, with its own keys.
+  const inRow = (el: HTMLElement) => !el.closest("[data-toolbar-more-panel]");
   const toolbarItems = () =>
     Array.from(toolbarRef.current?.querySelectorAll<HTMLButtonElement>("[data-toolbar-item]") ?? [])
-      .filter((el) => !el.disabled);
+      .filter((el) => !el.disabled && inRow(el));
   const syncToolbarTabStops = (focus?: HTMLButtonElement) => {
-    const all = Array.from(toolbarRef.current?.querySelectorAll<HTMLButtonElement>("[data-toolbar-item]") ?? []);
+    const all = Array.from(toolbarRef.current?.querySelectorAll<HTMLButtonElement>("[data-toolbar-item]") ?? []).filter(inRow);
     const enabled = all.filter((el) => !el.disabled);
     const current = focus ?? enabled.find((el) => el.dataset.toolbarItem === rovingItemRef.current) ?? enabled[0];
     if (current) rovingItemRef.current = current.dataset.toolbarItem ?? null;
@@ -740,6 +791,36 @@ export function RichTextEditor({
     return !!stop && document.activeElement === stop;
   };
 
+  // One row: what doesn't fit goes behind "More formatting" (a wrapped
+  // second row took the body's room in a narrow composer).
+  const [foldCount, setFoldCount] = useState(0);
+  const [moreOpen, setMoreOpen] = useState(false);
+  const moreButtonRef = useRef<HTMLButtonElement>(null);
+  const moreWrapperRef = useRef<HTMLDivElement>(null);
+  const hasEditor = !!editor;
+  useLayoutEffect(() => {
+    const toolbar = toolbarRef.current;
+    if (!toolbar) return;
+    const measure = () => setFoldCount(measureFormattingToolbar(toolbar, !!rtlEditingSupport));
+    measure();
+    if (typeof ResizeObserver === "undefined") return;
+    const observer = new ResizeObserver(() => {
+      measure();
+      setMoreOpen(false);
+    });
+    observer.observe(toolbar);
+    return () => observer.disconnect();
+  }, [hasEditor, rtlEditingSupport]);
+
+  useEffect(() => {
+    if (!moreOpen) return;
+    const handler = (e: MouseEvent) => {
+      if (moreWrapperRef.current && !moreWrapperRef.current.contains(e.target as Node)) setMoreOpen(false);
+    };
+    document.addEventListener("mousedown", handler);
+    return () => document.removeEventListener("mousedown", handler);
+  }, [moreOpen]);
+
   useEffect(() => {
     if (!fontSizeMenuOpen) return;
     const handler = (e: MouseEvent) => {
@@ -799,6 +880,15 @@ export function RichTextEditor({
   const altTarget = findAltTarget(editor, altRequest);
   const imageSelected = editor.isActive("image");
 
+  // A group that doesn't fit renders in the "More formatting" panel instead, in row order.
+  const folded = new Set<FoldableGroup>(FOLDABLE_GROUPS.slice(0, foldCount).map((group) => group.id));
+  const overflow: React.ReactNode[] = [];
+  const place = (group: FoldableGroup, node: React.ReactNode) => {
+    if (!folded.has(group)) return node;
+    overflow.push(<React.Fragment key={group}>{node}</React.Fragment>);
+    return null;
+  };
+
   const onToolbarKeyDown = (e: React.KeyboardEvent<HTMLDivElement>) => {
     const target = e.target as HTMLElement;
     // Keys inside a popover are the popover's.
@@ -819,7 +909,7 @@ export function RichTextEditor({
   };
   const onToolbarFocus = (e: React.FocusEvent<HTMLDivElement>) => {
     const target = e.target as HTMLElement;
-    if (target instanceof HTMLButtonElement && target.hasAttribute("data-toolbar-item")) syncToolbarTabStops(target);
+    if (target instanceof HTMLButtonElement && target.hasAttribute("data-toolbar-item") && inRow(target)) syncToolbarTabStops(target);
   };
 
   const renderPalette = (current: string | null, apply: (color: string) => void, removeLabel: string, remove: () => void) => (
@@ -1084,6 +1174,7 @@ export function RichTextEditor({
 
         <ToolbarSeparator />
 
+        {place("headings", <>
         <ToolbarButton
           item="heading-1"
           pressed={editor.isActive("heading", { level: 1 })}
@@ -1102,6 +1193,7 @@ export function RichTextEditor({
         </ToolbarButton>
 
         <ToolbarSeparator />
+        </>)}
 
         <ToolbarButton
           item="bullet-list"
@@ -1119,6 +1211,7 @@ export function RichTextEditor({
         >
           <ListOrdered className="w-4 h-4" />
         </ToolbarButton>
+        {place("blocks", <>
         <ToolbarButton
           item="quote"
           pressed={editor.isActive("blockquote")}
@@ -1135,9 +1228,11 @@ export function RichTextEditor({
         >
           <Code className="w-4 h-4" />
         </ToolbarButton>
+        </>)}
 
         <ToolbarSeparator />
 
+        {place("align", <>
         <ToolbarButton
           item="align-left"
           pressed={editor.isActive({ textAlign: "left" })}
@@ -1181,6 +1276,7 @@ export function RichTextEditor({
         )}
 
         <ToolbarSeparator />
+        </>)}
 
         <ToolbarButton
           item="link"
@@ -1205,7 +1301,7 @@ export function RichTextEditor({
           </ToolbarButton>
         )}
 
-        <div ref={tableWrapperRef} className="relative">
+        {place("table", <div ref={tableWrapperRef} className="relative">
           <ToolbarButton
             ref={tableButtonRef}
             item="table"
@@ -1257,8 +1353,9 @@ export function RichTextEditor({
               </ToolbarPopover>
             )
           )}
-        </div>
+        </div>)}
 
+        {place("history", <>
         <ToolbarSeparator />
 
         <ToolbarButton
@@ -1287,6 +1384,35 @@ export function RichTextEditor({
         >
           <Redo className="w-4 h-4" />
         </ToolbarButton>
+        </>)}
+
+        {overflow.length > 0 && (
+          <div ref={moreWrapperRef} className="relative">
+            <ToolbarButton
+              ref={moreButtonRef}
+              item="more-formatting"
+              popup="dialog"
+              expanded={moreOpen}
+              onClick={() => setMoreOpen((v) => !v)}
+              title={tWindows("more_formatting")}
+            >
+              <Ellipsis className="w-4 h-4" />
+            </ToolbarButton>
+            {moreOpen && (
+              <ToolbarPopover
+                label={tWindows("more_formatting")}
+                role="dialog"
+                triggerRef={moreButtonRef}
+                onClose={() => setMoreOpen(false)}
+                className="p-1 flex w-max max-w-[16rem] flex-wrap items-center gap-0.5"
+              >
+                <div data-toolbar-more-panel="" className="contents">
+                  {overflow}
+                </div>
+              </ToolbarPopover>
+            )}
+          </div>
+        )}
       </div>
 
       {/* Editor */}
diff --git a/components/popout/__tests__/popout-compose-app.test.tsx b/components/popout/__tests__/popout-compose-app.test.tsx
index 6ceedf1fa..d92e90439 100644
--- a/components/popout/__tests__/popout-compose-app.test.tsx
+++ b/components/popout/__tests__/popout-compose-app.test.tsx
@@ -4,6 +4,7 @@ import { FakeBroadcastChannel } from '@/lib/__tests__/fixtures/fake-broadcast-ch
 import { openPopoutChannel, type PopoutMessage, type RescuedDraft } from '@/lib/popout/channel';
 import { createComposeHandoff, rememberComposePayload, rememberedComposePayload } from '@/lib/popout/compose-handoff';
 import { useAuthStore } from '@/stores/auth-store';
+import { useEmailStore } from '@/stores/email-store';
 import { useIdentityStore } from '@/stores/identity-store';
 import { usePluginStore } from '@/stores/plugin-store';
 import { emailHooks } from '@/lib/plugin-hooks';
@@ -547,3 +548,90 @@ describe('after this page crashed', () => {
     expect(rememberedComposePayload('h2')).toBeNull();
   });
 });
+
+describe('a send held for undo', () => {
+  const closeSelf = vi.fn();
+  const MAILBOXES = [{ id: 'mDrafts', role: 'drafts' }, { id: 'mSent', role: 'sent' }];
+  const startDraft = {
+    id: 'd0', subject: 'Before sending', to: [{ email: 'a@example.org' }], cc: [], bcc: [], from: [{ name: 'Me', email: 'me@example.org' }],
+    keywords: { $draft: true }, mailboxIds: { mDrafts: true },
+    bodyValues: { t: { value: 'Text' } }, textBody: [{ partId: 't', type: 'text/plain' }], htmlBody: [], attachments: [],
+  };
+  const restoredDraft = {
+    id: 'e1', subject: 'Back again', to: [{ email: 'a@example.org' }], cc: [], bcc: [], from: [{ name: 'Me', email: 'me@example.org' }],
+    keywords: { $draft: true }, mailboxIds: { mDrafts: true },
+    bodyValues: { t: { value: 'Text' } }, textBody: [{ partId: 't', type: 'text/plain' }], htmlBody: [], attachments: [],
+  };
+  let originalEmail: ReturnType<typeof useEmailStore.getState>;
+  let sendAt: string;
+  let cancelUndoSend: ReturnType<typeof vi.fn>;
+
+  beforeEach(() => {
+    closeSelf.mockClear();
+    originalEmail = useEmailStore.getState();
+    window.bulwarkDesktop = { version: 1, platform: 'win32', windows: { closeSelf, setRestore: vi.fn() } } as never;
+    useIdentityStore.setState({ identities: [{ id: 'id-1', email: 'me@example.org', name: 'Me' }] } as never);
+    identityMocks.multi = { enabled: false, allIdentities: [], groups: [] };
+    const client = { getEmail: vi.fn(async (id: string) => (id === 'e1' ? restoredDraft : startDraft)), getMailboxes: vi.fn(async () => MAILBOXES) };
+    useAuthStore.setState({ client: client as never, getClientForAccount: (id: string) => (id === 'alice' ? client : undefined) } as never);
+    cancelUndoSend = vi.fn(async () => restoredDraft);
+    useEmailStore.setState({
+      sendEmail: vi.fn(async () => {
+        useEmailStore.setState({ pendingUndoSend: { submissionId: 'sub1', emailId: 'e1', identityId: 'id-1', sendAt, isSmime: false } });
+        return { scheduled: true, emailSubmissionId: 'sub1', emailId: 'e1', sendAt };
+      }),
+      cancelUndoSend,
+    } as never);
+  });
+
+  afterEach(() => {
+    useEmailStore.setState(originalEmail);
+    window.bulwarkDesktop = undefined;
+  });
+
+  type Sending = { onSend: (data: object) => Promise<unknown>; onClose: () => void };
+  const DATA = { to: ['a@example.org'], cc: [], bcc: [], subject: 'Hi', body: 'Text', localAccountId: 'alice' };
+
+  /** Opens the window, sends from it and lets the composer close, as it does after a send. */
+  async function sendFromWindow(seconds: number) {
+    sendAt = new Date(Date.now() + seconds * 1000).toISOString();
+    window.history.replaceState(null, '', '/en/popout/compose?draft=d0&account=alice');
+    render(<PopoutComposeApp />);
+    await waitFor(() => expect(screen.getByTestId('composer').textContent).toBe('Before sending'));
+    const props = composer as unknown as Sending;
+    await act(async () => { await props.onSend(DATA); });
+    act(() => props.onClose());
+  }
+
+  it('stays open with "Sending in" and Undo, and does not hand the undo to the main window', async () => {
+    await sendFromWindow(5);
+    expect(screen.getByTestId('popout-sending').textContent).toContain('sending_in');
+    expect(screen.getByRole('button', { name: 'undo_send' })).toBeInTheDocument();
+    expect(closeSelf).not.toHaveBeenCalled();
+    const sent = heard.find((message) => message.type === 'sent') as Extract<PopoutMessage, { type: 'sent' }> | undefined;
+    expect(sent?.notice.pendingUndoSend ?? null).toBeNull();
+  });
+
+  it('closes once the undo time is over', async () => {
+    await sendFromWindow(1.2);
+    expect(closeSelf).not.toHaveBeenCalled();
+    await waitFor(() => expect(closeSelf).toHaveBeenCalled(), { timeout: 4000 });
+  });
+
+  it('Undo takes the send back and opens the message again in this window', async () => {
+    await sendFromWindow(30);
+    fireEvent.click(screen.getByRole('button', { name: 'undo_send' }));
+    await waitFor(() => expect(cancelUndoSend).toHaveBeenCalledWith(expect.anything(), expect.objectContaining({ submissionId: 'sub1', localAccountId: 'alice' })));
+    await waitFor(() => expect(screen.getByTestId('composer').textContent).toBe('Back again'));
+    expect(closeSelf).not.toHaveBeenCalled();
+    expect(new URLSearchParams(window.location.search).get('draft')).toBe('e1');
+  });
+
+  it('a message scheduled for later still goes to the main window, and the window closes', async () => {
+    await sendFromWindow(3600);
+    expect(screen.queryByTestId('popout-sending')).toBeNull();
+    expect(closeSelf).toHaveBeenCalled();
+    const sent = heard.find((message) => message.type === 'sent') as Extract<PopoutMessage, { type: 'sent' }> | undefined;
+    expect(sent?.notice.pendingUndoSend?.submissionId).toBe('sub1');
+  });
+});
diff --git a/components/popout/__tests__/popout-host.test.tsx b/components/popout/__tests__/popout-host.test.tsx
index e8a0dd03e..1627d07a7 100644
--- a/components/popout/__tests__/popout-host.test.tsx
+++ b/components/popout/__tests__/popout-host.test.tsx
@@ -92,9 +92,20 @@ afterEach(() => {
 
 const answers = () => heard.filter((message) => message.type === 'session-answer');
 
-describe('in an ordinary browser tab', () => {
+/** A browser tab: not installed, with or without a mouse. */
+function stubTab(fine: boolean) {
+  delete window.bulwarkDesktop;
+  vi.stubGlobal('matchMedia', (query: string) => ({
+    matches: query.includes('pointer: fine') ? fine : false,
+    addEventListener() {},
+    removeEventListener() {},
+  }));
+  window.matchMedia = globalThis.matchMedia;
+}
+
+describe('in a browser tab on a phone or tablet', () => {
   it('runs nothing: no channel and no lock', async () => {
-    delete window.bulwarkDesktop;
+    stubTab(false);
     const opened = FakeBroadcastChannel.open.size;
     render(<PopoutHost />);
     await settle();
@@ -106,6 +117,18 @@ describe('in an ordinary browser tab', () => {
   });
 });
 
+describe('in a browser tab on a computer', () => {
+  it('lends its session to a composer popped out of it', async () => {
+    stubTab(true);
+    render(<PopoutHost />);
+    await settle();
+    await expect(requestWindowSession({}, 2000)).resolves.toMatchObject({
+      activeAccountId: 'alice',
+      sessions: [{ accountId: 'alice', authMode: 'oauth' }],
+    });
+  });
+});
+
 describe('PopoutHost', () => {
   it('holds no lock while idle, which would keep the page out of the back/forward cache', async () => {
     render(<PopoutHost />);
diff --git a/components/popout/popout-compose-app.tsx b/components/popout/popout-compose-app.tsx
index 4b9f058a8..e29b8810d 100644
--- a/components/popout/popout-compose-app.tsx
+++ b/components/popout/popout-compose-app.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useCallback, useEffect, useMemo, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { useTranslations } from "next-intl";
 import { EmailComposer, type ComposerDraftData } from "@/components/email/email-composer";
 import { ErrorBoundary, ComposerErrorFallback } from "@/components/error";
@@ -13,8 +13,9 @@ import { toast } from "@/stores/toast-store";
 import { formatRejectedRecipients } from "@/lib/jmap/client";
 import { debug } from "@/lib/debug";
 import { composerSendOptions } from "@/lib/outgoing/composer-send-options";
-import { announceSent } from "@/lib/plugin-after-send";
-import { announceMailChanged, announceSentToMainWindow, askRescuedDraftId, watchMainWindow, type RescuedDraft } from "@/lib/popout/channel";
+import { announceSent, cancelAnnouncedSend, releaseAnnouncedSend } from "@/lib/plugin-after-send";
+import { cancelFailureToast } from "@/lib/send-failure-message";
+import { announceMailChanged, announceSentToMainWindow, askRescuedDraftId, watchMainWindow, type PopoutSentNotice, type RescuedDraft } from "@/lib/popout/channel";
 import { acknowledgeComposeHandoff, forgetComposePayload, receiveComposeHandoff, rememberComposePayload, rememberedComposePayload, watchHandoffCancel } from "@/lib/popout/compose-handoff";
 import type { ComposePopoutPayload } from "@/lib/popout/compose-payload";
 import { returnComposerToMain, type ReturnResult } from "@/lib/popout/return-to-main";
@@ -30,6 +31,7 @@ import { emailHooks } from "@/lib/plugin-hooks";
 import { useProMultiAccountIdentities } from "@/hooks/use-pro-multi-account-identities";
 import { useIdentityStore } from "@/stores/identity-store";
 import type { Email } from "@/lib/jmap/types";
+import { Send } from "@/components/icons";
 import { PopoutNotice, PopoutShell, PopoutSkeleton } from "./popout-shell";
 
 /** A warning with no main window left to show it stays this long before the window goes. */
@@ -49,6 +51,91 @@ const MAIN_CHECK_MS = 1000;
 /** How long a reloaded window waits to hear what became of the text it handed over on the way out. */
 const RESCUE_ANSWER_MS = 2000;
 
+/** A send held this long or less is an undo window ("Sending in 5 s"), not a message scheduled for later. */
+const UNDO_WINDOW_MS = 120_000;
+/** Undo goes this long before the server lets the message go, as in the main window. */
+const UNDO_MARGIN_MS = 1000;
+/** What the plugins are told when the hold runs out gets this long before the window goes. */
+const RELEASE_WAIT_MS = 1000;
+
+type HeldSend = NonNullable<PopoutSentNotice["pendingUndoSend"]>;
+
+/** A draft to open again in this window, after Undo brought the message back to Drafts. */
+interface ReopenTarget {
+  draftId: string;
+  accountId: string;
+  ownerAccountId?: string;
+}
+
+/**
+ * A send held for undo, shown in the window it was sent from: that's where the
+ * user is looking, and quick compose is used with the main window out of sight.
+ * The window stays until the hold runs out, then goes.
+ */
+function SendingWithUndo({ held, onUndone, onGone }: {
+  held: HeldSend;
+  /** The send was taken back; the message, back in Drafts, when there is one to open. */
+  onUndone: (restored: Email | null) => void;
+  onGone: () => void;
+}) {
+  const tViewer = useTranslations("email_viewer");
+  const [now, setNow] = useState(() => Date.now());
+  const [busy, setBusy] = useState(false);
+  const sendAt = Date.parse(held.sendAt);
+  const over = !Number.isFinite(sendAt) || now >= sendAt - UNDO_MARGIN_MS;
+
+  useEffect(() => {
+    if (over) return;
+    const timer = setInterval(() => setNow(Date.now()), 250);
+    return () => clearInterval(timer);
+  }, [over]);
+
+  // Too late to undo: the plugins hear of the send now, and the window goes.
+  useEffect(() => {
+    if (!over || busy) return;
+    releaseAnnouncedSend(held.submissionId);
+    const timer = setTimeout(onGone, RELEASE_WAIT_MS);
+    return () => clearTimeout(timer);
+  }, [over, busy, held.submissionId, onGone]);
+
+  const undo = async () => {
+    const auth = useAuthStore.getState();
+    // Never another login: the submission id names another submission there.
+    const client = held.localAccountId ? auth.getClientForAccount(held.localAccountId) : auth.client;
+    if (!client) {
+      toast.error(tViewer("undo_send_signed_out"));
+      return;
+    }
+    setBusy(true);
+    let restored: Email | null;
+    try {
+      restored = await useEmailStore.getState().cancelUndoSend(client, held);
+    } catch (error) {
+      debug.error("Failed to undo the send:", error);
+      const { title, message } = cancelFailureToast(error, tViewer, tViewer("undo_send_failed"));
+      toast.error(title, message ? { message } : undefined);
+      setBusy(false);
+      return;
+    }
+    // Never left the server: plugins don't hear about it.
+    cancelAnnouncedSend(held.submissionId);
+    onUndone(held.isSmime ? null : restored);
+  };
+
+  const seconds = Math.max(0, Math.ceil((sendAt - now) / 1000));
+  return (
+    <div className="flex min-h-0 flex-1 flex-col items-center justify-center gap-4 p-6 text-center" data-testid="popout-sending">
+      <Send className="h-6 w-6 text-muted-foreground" aria-hidden="true" />
+      <p role="status" className="text-sm text-foreground">{tViewer("sending_in", { seconds })}</p>
+      {!over && (
+        <Button onClick={() => void undo()} disabled={busy} data-testid="popout-undo-send">
+          {tViewer("undo_send")}
+        </Button>
+      )}
+    </div>
+  );
+}
+
 function readLaunch(): { handoffId: string | null; accountId?: string; draftId?: string; ownerAccountId?: string } {
   if (typeof window === "undefined") return { handoffId: null };
   const search = new URLSearchParams(window.location.search);
@@ -214,7 +301,12 @@ function NewMessageGate({ onReady }: { onReady: (payload: ComposePopoutPayload)
 }
 
 /** The composer alone, in its own window: sending, autosave and discard go through the shared stores, as in a Pro tab. */
-function PopoutComposer({ payload, handoffId }: { payload: ComposePopoutPayload; handoffId: string | null }) {
+function PopoutComposer({ payload, handoffId, onReopen }: {
+  payload: ComposePopoutPayload;
+  handoffId: string | null;
+  /** Undo brought the message back to Drafts: open it again here. */
+  onReopen: (target: ReopenTarget) => void;
+}) {
   const t = useTranslations();
   const tQuick = useTranslations("desktopQuickCompose");
   const client = useAuthStore((s) => s.client);
@@ -267,6 +359,16 @@ function PopoutComposer({ payload, handoffId }: { payload: ComposePopoutPayload;
 
     const accountId = data.localAccountId ?? useAuthStore.getState().activeAccountId;
     const pending = useEmailStore.getState().pendingUndoSend;
+    const withLogin = pending ? { ...pending, localAccountId: pending.localAccountId ?? accountId ?? undefined } : null;
+    // An undo window stays here, where Send was pressed: the window shows it
+    // and closes when it runs out. A message scheduled for later goes to the
+    // main window as before.
+    const remaining = withLogin ? Date.parse(withLogin.sendAt) - Date.now() : NaN;
+    const keepHere = result.scheduled && withLogin && Number.isFinite(remaining) && remaining <= UNDO_WINDOW_MS ? withLogin : null;
+    if (keepHere) {
+      heldRef.current = keepHere;
+      useEmailStore.setState({ pendingUndoSend: null });
+    }
     const rejectedRecipients = result.rejectedRecipients?.length ? formatRejectedRecipients(result.rejectedRecipients) : undefined;
     const taken = await announceSentToMainWindow({
       accountId,
@@ -274,7 +376,7 @@ function PopoutComposer({ payload, handoffId }: { payload: ComposePopoutPayload;
       queued: !!result.queued,
       filingError: !!result.filingError,
       rejectedRecipients,
-      pendingUndoSend: pending ? { ...pending, localAccountId: pending.localAccountId ?? accountId ?? undefined } : null,
+      pendingUndoSend: keepHere ? null : withLogin,
     });
     // No main window to say so, and this is the only notice these get (#1123).
     if (!taken && (result.filingError || rejectedRecipients)) {
@@ -301,11 +403,36 @@ function PopoutComposer({ payload, handoffId }: { payload: ComposePopoutPayload;
     }
   }, [client, t]);
 
+  // A send held for undo, kept in this window until it runs out.
+  const heldRef = useRef<HeldSend | null>(null);
+  const [held, setHeld] = useState<HeldSend | null>(null);
+
   const handleClose = useCallback(() => {
+    announceMailChanged(useAuthStore.getState().activeAccountId);
+    if (heldRef.current) {
+      setHeld(heldRef.current);
+      return;
+    }
+    closePopoutWindow();
+  }, []);
+
+  const heldGone = useCallback(() => {
     announceMailChanged(useAuthStore.getState().activeAccountId);
     closePopoutWindow();
   }, []);
 
+  const heldUndone = useCallback((restored: Email | null) => {
+    const sent = heldRef.current;
+    heldRef.current = null;
+    const login = sent?.localAccountId ?? useAuthStore.getState().activeAccountId;
+    announceMailChanged(login);
+    if (!restored || !login) {
+      closePopoutWindow();
+      return;
+    }
+    onReopen({ draftId: restored.id, accountId: login, ownerAccountId: sent?.submissionAccountId });
+  }, [onReopen]);
+
   const [mainWindow] = useState(watchMainWindow);
   useEffect(() => () => mainWindow.stop(), [mainWindow]);
 
@@ -373,6 +500,8 @@ function PopoutComposer({ payload, handoffId }: { payload: ComposePopoutPayload;
     },
   }), [handoffId, mainWindow, payload]);
 
+  if (held) return <SendingWithUndo held={held} onUndone={heldUndone} onGone={heldGone} />;
+
   return (
     <ErrorBoundary fallback={ComposerErrorFallback}>
       <EmailComposer
@@ -405,6 +534,26 @@ export function PopoutComposeApp() {
   // draft is the newest there is. An ordinary reload remembers as it unloads.
   const [handoffId] = useState(() => (named && draftId && !rememberedComposePayload(named) ? null : named));
   const [payload, setPayload] = useState<ComposePopoutPayload | null>(null);
+  // After Undo: the message back in Drafts, opened again in a new composer here.
+  const [reopen, setReopen] = useState<ReopenTarget | null>(null);
+  const [generation, setGeneration] = useState(0);
+  const handleReopen = useCallback((target: ReopenTarget) => {
+    // A reload starts from the draft, as after a save.
+    const url = new URL(window.location.href);
+    url.searchParams.delete("handoff");
+    url.searchParams.set("draft", target.draftId);
+    url.searchParams.set("account", target.accountId);
+    if (target.ownerAccountId) url.searchParams.set("owner", target.ownerAccountId);
+    else url.searchParams.delete("owner");
+    window.history.replaceState(null, "", `${url.pathname}${url.search}`);
+    setPayload(null);
+    setReopen(target);
+  }, []);
+  const reopened = useCallback((next: ComposePopoutPayload) => {
+    setReopen(null);
+    setGeneration((n) => n + 1);
+    setPayload(next);
+  }, []);
 
   useEffect(() => {
     if (!handoffId) return;
@@ -438,7 +587,8 @@ export function PopoutComposeApp() {
 
   return (
     <PopoutShell kind="compose" accountId={accountId}>
-      {payload ? <PopoutComposer payload={payload} handoffId={handoffId} />
+      {payload ? <PopoutComposer key={generation} payload={payload} handoffId={generation === 0 ? handoffId : null} onReopen={handleReopen} />
+        : reopen ? <RestoredDraft draftId={reopen.draftId} accountId={reopen.accountId} ownerAccountId={reopen.ownerAccountId} onReady={reopened} />
         : handoffId ? <PopoutSkeleton label={t("opening")} />
         : draftId ? <RestoredDraft draftId={draftId} accountId={accountId} ownerAccountId={ownerAccountId} onReady={setPayload} />
         : <NewMessageGate onReady={setPayload} />}
diff --git a/components/popout/popout-host.tsx b/components/popout/popout-host.tsx
index 4239c73b6..fc7305e60 100644
--- a/components/popout/popout-host.tsx
+++ b/components/popout/popout-host.tsx
@@ -60,8 +60,9 @@ function claimOnce(name: string, work: () => void | Promise<void>): void {
 /**
  * The main window's side of pop-outs: lends them its session and renews it
  * for them, passes on that mail changed, and takes over what a pop-out can't
- * say any more once it has closed. Only where pop-outs are on offer: an
- * ordinary browser tab runs none of this.
+ * say any more once it has closed. Only where pop-outs are on offer: a
+ * browser tab on a computer runs it for composers popped out of it, one on a
+ * phone or tablet runs none of this.
  */
 export function PopoutHost() {
   const available = usePopoutsAvailable();
diff --git a/hooks/use-browser-online.ts b/hooks/use-browser-online.ts
new file mode 100644
index 000000000..00d6d86e1
--- /dev/null
+++ b/hooks/use-browser-online.ts
@@ -0,0 +1,21 @@
+"use client";
+
+import { useSyncExternalStore } from "react";
+
+function subscribe(onChange: () => void): () => void {
+  window.addEventListener("online", onChange);
+  window.addEventListener("offline", onChange);
+  return () => {
+    window.removeEventListener("online", onChange);
+    window.removeEventListener("offline", onChange);
+  };
+}
+
+/**
+ * Whether the browser says it has a network, kept up to date. Also without
+ * offline mode, whose store only follows it while that runs. True on the
+ * server and while the page hydrates.
+ */
+export function useBrowserOnline(): boolean {
+  return useSyncExternalStore(subscribe, () => navigator.onLine !== false, () => true);
+}
diff --git a/hooks/use-popouts-available.ts b/hooks/use-popouts-available.ts
index 7628846a0..9e391d73d 100644
--- a/hooks/use-popouts-available.ts
+++ b/hooks/use-popouts-available.ts
@@ -7,27 +7,30 @@ import { resolveEmailBlobContext } from "@/stores/email-store";
 import { toast } from "@/stores/toast-store";
 import type { Email } from "@/lib/jmap/types";
 import { openMessageWindow } from "@/lib/popout/open";
-import { popoutsAvailable } from "@/lib/popout/support";
+import { composerPopoutsAvailable, popoutsAvailable } from "@/lib/popout/support";
 import { isPopoutWindow } from "@/lib/popout/window-role";
 
 /**
- * Whether to offer "Open in new window" here. False on the server and in the
- * first render, so the markup hydrates the same; false in the demo, whose
- * client has no session to share, and inside a pop-out (for a message: it is
- * already in its own window).
+ * Whether to offer "Open in new window" here: for a composer, the default,
+ * also in a browser tab on a computer; for a message only in an installed or
+ * the desktop app. False on the server and in the first render, so the
+ * markup hydrates the same; false in the demo, whose client has no session to
+ * share, and inside a pop-out (for a message: it is already in its own window).
+ * The main window's side of pop-outs (PopoutHost) runs wherever a composer can
+ * move out.
  */
-export function usePopoutsAvailable(): boolean {
+export function usePopoutsAvailable(kind: "compose" | "message" = "compose"): boolean {
   const isDemoMode = useAuthStore((s) => s.isDemoMode);
   const [available, setAvailable] = useState(false);
   useEffect(() => {
-    const check = () => setAvailable(popoutsAvailable() && !isPopoutWindow());
+    const check = () => setAvailable((kind === "message" ? popoutsAvailable() : composerPopoutsAvailable()) && !isPopoutWindow());
     check();
     // Installing the running tab turns it into a window without a reload.
     if (typeof window.matchMedia !== "function") return;
     const media = window.matchMedia("(display-mode: standalone)");
     media.addEventListener?.("change", check);
     return () => media.removeEventListener?.("change", check);
-  }, []);
+  }, [kind]);
   return available && !isDemoMode;
 }
 
@@ -37,7 +40,7 @@ export function usePopoutsAvailable(): boolean {
  * blocks the window; nothing else changes then.
  */
 export function useOpenEmailInWindow(): ((email: Email) => void) | null {
-  const available = usePopoutsAvailable();
+  const available = usePopoutsAvailable("message");
   const t = useTranslations("pwaWindows");
   const open = useCallback((email: Email) => {
     const auth = useAuthStore.getState();
diff --git a/lib/__tests__/popout-windows.test.ts b/lib/__tests__/popout-windows.test.ts
index f3675c552..a041f2114 100644
--- a/lib/__tests__/popout-windows.test.ts
+++ b/lib/__tests__/popout-windows.test.ts
@@ -132,6 +132,53 @@ describe('popoutsAvailable', () => {
   });
 });
 
+describe('composerPopoutsAvailable', () => {
+  async function available() {
+    const { composerPopoutsAvailable } = await import('@/lib/popout/support');
+    return composerPopoutsAvailable();
+  }
+
+  it('is on in a browser tab on a computer: a composer opens as a popup window, as in Gmail', async () => {
+    stubDisplay({ standalone: false });
+    expect(await available()).toBe(true);
+  });
+
+  it('is off in a browser tab on a phone or tablet, where window.open makes a tab', async () => {
+    stubDisplay({ standalone: false, fine: false });
+    expect(await available()).toBe(false);
+  });
+
+  it('is on wherever a message can move out too', async () => {
+    stubDisplay();
+    expect(await available()).toBe(true);
+    stubDisplay({ standalone: false, fine: false });
+    window.bulwarkDesktop = { version: 1, platform: 'win32', windows: {} };
+    expect(await available()).toBe(true);
+  });
+
+  it('is off in an installed app on a touch device', async () => {
+    stubDisplay({ fine: false });
+    expect(await available()).toBe(false);
+  });
+
+  it('is off in a tab without what keeps a shared session safe', async () => {
+    stubDisplay({ standalone: false });
+    vi.stubGlobal('BroadcastChannel', undefined);
+    expect(await available()).toBe(false);
+    vi.stubGlobal('BroadcastChannel', FakeBroadcastChannel);
+    vi.stubGlobal('crypto', {});
+    expect(await available()).toBe(false);
+  });
+
+  it('lets the hook offer a composer its own window from a tab, and still not a message', async () => {
+    stubDisplay({ standalone: false });
+    const { renderHook } = await import('@testing-library/react');
+    const { usePopoutsAvailable } = await import('@/hooks/use-popouts-available');
+    expect(renderHook(() => usePopoutsAvailable()).result.current).toBe(true);
+    expect(renderHook(() => usePopoutsAvailable('message')).result.current).toBe(false);
+  }, 60_000);
+});
+
 describe('opening windows', () => {
   it('opens a message as a popup in the app, with its login and account', async () => {
     const { openMessageWindow } = await import('@/lib/popout/open');
diff --git a/lib/popout/support.ts b/lib/popout/support.ts
index f06f22aeb..150a6380b 100644
--- a/lib/popout/support.ts
+++ b/lib/popout/support.ts
@@ -1,7 +1,8 @@
 /**
  * Whether "Open in new window" is on offer: an installed app or the desktop
  * app, on a device with windows. In a browser tab, a tab does the same job
- * and the app behaves as it always has.
+ * for a message, and the app behaves as it always has. A composer is the
+ * exception: it moves to a window of its own from a tab too, as in Gmail.
  */
 
 import { IS_LITE } from '@/lib/lite';
@@ -13,16 +14,36 @@ export function hasDesktopWindows(): boolean {
   return typeof window !== 'undefined' && !!window.bulwarkDesktop?.windows;
 }
 
-/** Display mode is `browser` in Electron popups too, hence the bridge check. */
-export function popoutsAvailable(): boolean {
+/** A second window can share this one's session, safely. */
+function windowsCanShareSessions(): boolean {
   // Lite has no such route: a static export can't list every message id.
   if (IS_LITE || typeof window === 'undefined') return false;
   // Sharing the session and renewing tokens safely across windows need these.
-  if (typeof BroadcastChannel === 'undefined' || !navigator.locks || !canSealSessions()) return false;
+  return typeof BroadcastChannel !== 'undefined' && !!navigator.locks && canSealSessions();
+}
+
+/** A device with a mouse or trackpad: a phone or tablet has no second window. */
+function hasFinePointer(): boolean {
+  return typeof window.matchMedia === 'function' && window.matchMedia('(pointer: fine)').matches;
+}
+
+/** Display mode is `browser` in Electron popups too, hence the bridge check. */
+export function popoutsAvailable(): boolean {
+  if (!windowsCanShareSessions()) return false;
   if (hasDesktopWindows()) return true;
   if (!isStandaloneDisplayMode()) return false;
   // A home-screen app on a phone or tablet has no second window: window.open
   // leaves for the browser there.
   if ((window.navigator as Navigator & { standalone?: boolean }).standalone === true) return false;
-  return typeof window.matchMedia === 'function' && window.matchMedia('(pointer: fine)').matches;
+  return hasFinePointer();
+}
+
+/**
+ * A composer can move to a window of its own: wherever a message can, and in
+ * a browser tab on a computer too, where it opens as a popup window.
+ */
+export function composerPopoutsAvailable(): boolean {
+  if (popoutsAvailable()) return true;
+  if (!windowsCanShareSessions() || isStandaloneDisplayMode()) return false;
+  return hasFinePointer();
 }
diff --git a/locales/ar/common.json b/locales/ar/common.json
index 68c8242b1..58c7fe5a6 100644
--- a/locales/ar/common.json
+++ b/locales/ar/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "تكتب هذه المفاتيح حرفًا على لوحة مفاتيحك، وسيتوقف عن العمل في كل التطبيقات. جرّب مفاتيح أخرى.",
     "reserved": "يستخدم النظام أو معظم التطبيقات هذه المفاتيح. جرّب مفاتيح أخرى."
   },
+  "compose_windows": {
+    "more_formatting": "مزيد من التنسيق",
+    "offline": "دون اتصال",
+    "offline_hint": "يحتاج الإرسال إلى اتصال.",
+    "offline_hint_outbox": "ما ترسله الآن ينتظر في صندوق الصادر ويُرسل عند عودة الاتصال.",
+    "offline_send_saved": "أنت دون اتصال. الرسالة محفوظة في المسودات.",
+    "offline_send_unsaved": "أنت دون اتصال. تبقى الرسالة هنا وتُحفظ في المسودات عند عودة الاتصال."
+  },
   "desktopReminders": {
     "generic_title": "تذكير",
     "snooze": "تأجيل {count} د",
diff --git a/locales/ca/common.json b/locales/ca/common.json
index b63bab5c3..e1da6608f 100644
--- a/locales/ca/common.json
+++ b/locales/ca/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Aquestes tecles escriuen un caràcter al teu teclat, i deixaria de funcionar a totes les aplicacions. Prova altres tecles.",
     "reserved": "El sistema o la majoria d'aplicacions fan servir aquestes tecles. Prova altres tecles."
   },
+  "compose_windows": {
+    "more_formatting": "Més format",
+    "offline": "Sense connexió",
+    "offline_hint": "Per enviar cal connexió.",
+    "offline_hint_outbox": "El que envieu ara espera a la safata de sortida i s'envia quan torneu a tenir connexió.",
+    "offline_send_saved": "No teniu connexió. El missatge està desat a Esborranys.",
+    "offline_send_unsaved": "No teniu connexió. El missatge es queda aquí i es desa a Esborranys quan torneu a tenir connexió."
+  },
   "desktopReminders": {
     "generic_title": "Recordatori",
     "snooze": "Posposa {count} min",
diff --git a/locales/cs/common.json b/locales/cs/common.json
index 6b0cf3b1a..fa9b5d3c8 100644
--- a/locales/cs/common.json
+++ b/locales/cs/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Tyto klávesy na vaší klávesnici píší znak, který by pak nefungoval v žádné aplikaci. Zkuste jiné klávesy.",
     "reserved": "Tyto klávesy používá systém nebo většina aplikací. Zkuste jiné klávesy."
   },
+  "compose_windows": {
+    "more_formatting": "Další formátování",
+    "offline": "Offline",
+    "offline_hint": "Odeslání potřebuje připojení.",
+    "offline_hint_outbox": "Co teď odešlete, počká mezi zprávami k odeslání a odejde, až budete znovu online.",
+    "offline_send_saved": "Jste offline. Zpráva je uložená v Konceptech.",
+    "offline_send_unsaved": "Jste offline. Zpráva tu zůstane a uloží se do Konceptů, až budete znovu online."
+  },
   "desktopReminders": {
     "generic_title": "Připomenutí",
     "snooze": "Odložit o {count} min",
diff --git a/locales/da/common.json b/locales/da/common.json
index aca6afafd..656cadee7 100644
--- a/locales/da/common.json
+++ b/locales/da/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Disse taster skriver et tegn på dit tastatur, og det ville holde op med at virke i alle apps. Prøv andre taster.",
     "reserved": "Dit system eller de fleste apps bruger disse taster. Prøv andre taster."
   },
+  "compose_windows": {
+    "more_formatting": "Mere formatering",
+    "offline": "Offline",
+    "offline_hint": "Det kræver forbindelse at sende.",
+    "offline_hint_outbox": "Det, du sender nu, venter i udbakken og sendes, når du er online igen.",
+    "offline_send_saved": "Du er offline. Beskeden er gemt i Kladder.",
+    "offline_send_unsaved": "Du er offline. Beskeden bliver her og gemmes i Kladder, når du er online igen."
+  },
   "desktopReminders": {
     "generic_title": "Påmindelse",
     "snooze": "Udsæt {count} min.",
diff --git a/locales/de/common.json b/locales/de/common.json
index 884536e57..55853ac55 100644
--- a/locales/de/common.json
+++ b/locales/de/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Diese Tasten erzeugen auf Ihrer Tastatur ein Zeichen, das dann in keiner App mehr funktionieren würde. Versuchen Sie andere Tasten.",
     "reserved": "Ihr System oder die meisten Apps verwenden diese Tasten. Versuchen Sie andere Tasten."
   },
+  "compose_windows": {
+    "more_formatting": "Weitere Formatierung",
+    "offline": "Offline",
+    "offline_hint": "Zum Senden ist eine Verbindung nötig.",
+    "offline_hint_outbox": "Was Sie jetzt senden, wartet im Postausgang und wird gesendet, sobald Sie wieder online sind.",
+    "offline_send_saved": "Sie sind offline. Die Nachricht ist in den Entwürfen gespeichert.",
+    "offline_send_unsaved": "Sie sind offline. Die Nachricht bleibt hier und wird in den Entwürfen gespeichert, sobald Sie wieder online sind."
+  },
   "desktopReminders": {
     "generic_title": "Erinnerung",
     "snooze": "{count} Min. schlummern",
diff --git a/locales/en/common.json b/locales/en/common.json
index 15de2fb71..d3304d888 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "These keys type a character on your keyboard, and it would stop working in every app. Try other keys.",
     "reserved": "Your system or most apps use these keys. Try other keys."
   },
+  "compose_windows": {
+    "more_formatting": "More formatting",
+    "offline": "Offline",
+    "offline_hint": "Sending needs a connection.",
+    "offline_hint_outbox": "What you send now waits in the outbox and goes out when you're back online.",
+    "offline_send_saved": "You're offline. The message is saved in Drafts.",
+    "offline_send_unsaved": "You're offline. The message stays here and is saved in Drafts when you're back online."
+  },
   "desktopReminders": {
     "generic_title": "Reminder",
     "snooze": "Snooze {count} min",
diff --git a/locales/es/common.json b/locales/es/common.json
index bb91610a8..f36dde45f 100644
--- a/locales/es/common.json
+++ b/locales/es/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Estas teclas escriben un carácter en tu teclado, y dejaría de funcionar en todas las aplicaciones. Prueba otras teclas.",
     "reserved": "Tu sistema o la mayoría de las aplicaciones usan estas teclas. Prueba otras teclas."
   },
+  "compose_windows": {
+    "more_formatting": "Más formato",
+    "offline": "Sin conexión",
+    "offline_hint": "Para enviar hace falta conexión.",
+    "offline_hint_outbox": "Lo que envíes ahora espera en la bandeja de salida y se envía cuando vuelvas a tener conexión.",
+    "offline_send_saved": "No tienes conexión. El mensaje está guardado en Borradores.",
+    "offline_send_unsaved": "No tienes conexión. El mensaje se queda aquí y se guarda en Borradores cuando vuelvas a tener conexión."
+  },
   "desktopReminders": {
     "generic_title": "Recordatorio",
     "snooze": "Posponer {count} min",
diff --git a/locales/et/common.json b/locales/et/common.json
index 158469544..696254787 100644
--- a/locales/et/common.json
+++ b/locales/et/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Need klahvid kirjutavad teie klaviatuuril märgi, mis lakkaks kõigis rakendustes töötamast. Proovige teisi klahve.",
     "reserved": "Neid klahve kasutab süsteem või enamik rakendusi. Proovige teisi klahve."
   },
+  "compose_windows": {
+    "more_formatting": "Rohkem vormindust",
+    "offline": "Võrguta",
+    "offline_hint": "Saatmiseks on vaja ühendust.",
+    "offline_hint_outbox": "Mida praegu saadad, ootab väljuvate kirjade kastis ja läheb teele, kui oled jälle võrgus.",
+    "offline_send_saved": "Oled võrguta. Kiri on salvestatud mustanditesse.",
+    "offline_send_unsaved": "Oled võrguta. Kiri jääb siia ja salvestatakse mustanditesse, kui oled jälle võrgus."
+  },
   "desktopReminders": {
     "generic_title": "Meeldetuletus",
     "snooze": "Lükka {count} min edasi",
diff --git a/locales/fa/common.json b/locales/fa/common.json
index 6e75c02ab..ea0ca72a2 100644
--- a/locales/fa/common.json
+++ b/locales/fa/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "این کلیدها روی صفحه‌کلید شما نویسه‌ای می‌نویسند و آن نویسه دیگر در هیچ برنامه‌ای کار نمی‌کند. کلیدهای دیگری را امتحان کنید.",
     "reserved": "سیستم یا بیشتر برنامه‌ها از این کلیدها استفاده می‌کنند. کلیدهای دیگری را امتحان کنید."
   },
+  "compose_windows": {
+    "more_formatting": "قالب‌بندی بیشتر",
+    "offline": "آفلاین",
+    "offline_hint": "ارسال به اتصال نیاز دارد.",
+    "offline_hint_outbox": "آنچه اکنون می‌فرستید در صندوق خروجی می‌ماند و وقتی دوباره آنلاین شدید فرستاده می‌شود.",
+    "offline_send_saved": "آفلاین هستید. پیام در پیش‌نویس‌ها ذخیره شده است.",
+    "offline_send_unsaved": "آفلاین هستید. پیام همین‌جا می‌ماند و وقتی دوباره آنلاین شدید در پیش‌نویس‌ها ذخیره می‌شود."
+  },
   "desktopReminders": {
     "generic_title": "یادآوری",
     "snooze": "تعویق {count} دقیقه",
diff --git a/locales/fr/common.json b/locales/fr/common.json
index 6ade6955d..0cb389ffd 100644
--- a/locales/fr/common.json
+++ b/locales/fr/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Ces touches produisent un caractère sur votre clavier, et il ne fonctionnerait plus dans aucune application. Essayez d'autres touches.",
     "reserved": "Votre système ou la plupart des applications utilisent ces touches. Essayez d'autres touches."
   },
+  "compose_windows": {
+    "more_formatting": "Plus de mise en forme",
+    "offline": "Hors ligne",
+    "offline_hint": "L'envoi nécessite une connexion.",
+    "offline_hint_outbox": "Ce que vous envoyez maintenant attend dans la boîte d'envoi et part dès que vous êtes de nouveau en ligne.",
+    "offline_send_saved": "Vous êtes hors ligne. Le message est enregistré dans les Brouillons.",
+    "offline_send_unsaved": "Vous êtes hors ligne. Le message reste ici et sera enregistré dans les Brouillons dès que vous serez de nouveau en ligne."
+  },
   "desktopReminders": {
     "generic_title": "Rappel",
     "snooze": "Reporter de {count} min",
diff --git a/locales/he/common.json b/locales/he/common.json
index 51bbe4dc8..d2b2dcbe6 100644
--- a/locales/he/common.json
+++ b/locales/he/common.json
@@ -7110,6 +7110,14 @@
     "types_character": "המקשים האלה מקלידים תו במקלדת שלכם, והוא יפסיק לעבוד בכל האפליקציות. נסו מקשים אחרים.",
     "reserved": "המערכת או רוב האפליקציות משתמשות במקשים האלה. נסו מקשים אחרים."
   },
+  "compose_windows": {
+    "more_formatting": "עוד עיצוב",
+    "offline": "אין חיבור",
+    "offline_hint": "כדי לשלוח צריך חיבור.",
+    "offline_hint_outbox": "מה ששולחים עכשיו ממתין בתיבת הדואר היוצא ונשלח כשחוזרים לרשת.",
+    "offline_send_saved": "אין חיבור. ההודעה שמורה בטיוטות.",
+    "offline_send_unsaved": "אין חיבור. ההודעה נשארת כאן ותישמר בטיוטות כשתחזרו לרשת."
+  },
   "desktopReminders": {
     "generic_title": "תזכורת",
     "snooze": "דחייה ב-{count} דק'",
diff --git a/locales/hu/common.json b/locales/hu/common.json
index cf6ef46e8..6ddc16963 100644
--- a/locales/hu/common.json
+++ b/locales/hu/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Ezek a billentyűk karaktert írnak az Ön billentyűzetén, amely többé egyik alkalmazásban sem működne. Próbáljon más billentyűket.",
     "reserved": "Ezeket a billentyűket a rendszer vagy a legtöbb alkalmazás használja. Próbáljon más billentyűket."
   },
+  "compose_windows": {
+    "more_formatting": "További formázás",
+    "offline": "Offline",
+    "offline_hint": "A küldéshez kapcsolat kell.",
+    "offline_hint_outbox": "Amit most elküld, a postázandók között vár, és elmegy, amint újra online lesz.",
+    "offline_send_saved": "Offline állapotban van. Az üzenet a Piszkozatok között van mentve.",
+    "offline_send_unsaved": "Offline állapotban van. Az üzenet itt marad, és a Piszkozatok közé kerül, amint újra online lesz."
+  },
   "desktopReminders": {
     "generic_title": "Emlékeztető",
     "snooze": "Halasztás {count} perccel",
diff --git a/locales/it/common.json b/locales/it/common.json
index 036794cb5..199d681a8 100644
--- a/locales/it/common.json
+++ b/locales/it/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Questi tasti scrivono un carattere sulla tua tastiera, che smetterebbe di funzionare in tutte le app. Prova altri tasti.",
     "reserved": "Il sistema o la maggior parte delle app usano questi tasti. Prova altri tasti."
   },
+  "compose_windows": {
+    "more_formatting": "Altre opzioni di formattazione",
+    "offline": "Offline",
+    "offline_hint": "Per inviare serve una connessione.",
+    "offline_hint_outbox": "Quello che invii ora aspetta nella posta in uscita e parte quando torni online.",
+    "offline_send_saved": "Sei offline. Il messaggio è salvato nelle Bozze.",
+    "offline_send_unsaved": "Sei offline. Il messaggio resta qui e viene salvato nelle Bozze quando torni online."
+  },
   "desktopReminders": {
     "generic_title": "Promemoria",
     "snooze": "Rimanda di {count} min",
diff --git a/locales/ja/common.json b/locales/ja/common.json
index 8fba56594..fd47c9e9b 100644
--- a/locales/ja/common.json
+++ b/locales/ja/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "このキーはお使いのキーボードで文字を入力します。割り当てると、すべてのアプリでその文字を入力できなくなります。別のキーをお試しください。",
     "reserved": "このキーはシステムまたは多くのアプリが使用しています。別のキーをお試しください。"
   },
+  "compose_windows": {
+    "more_formatting": "その他の書式",
+    "offline": "オフライン",
+    "offline_hint": "送信には接続が必要です。",
+    "offline_hint_outbox": "今送信したものは送信トレイで待機し、オンラインに戻ると送信されます。",
+    "offline_send_saved": "オフラインです。メッセージは下書きに保存されています。",
+    "offline_send_unsaved": "オフラインです。メッセージはここに残り、オンラインに戻ると下書きに保存されます。"
+  },
   "desktopReminders": {
     "generic_title": "リマインダー",
     "snooze": "{count} 分後に再通知",
diff --git a/locales/ko/common.json b/locales/ko/common.json
index 70a3b58bf..a6fde0874 100644
--- a/locales/ko/common.json
+++ b/locales/ko/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "이 키는 사용 중인 키보드에서 문자를 입력하며, 지정하면 모든 앱에서 그 문자를 입력할 수 없게 됩니다. 다른 키를 사용해 보세요.",
     "reserved": "시스템 또는 대부분의 앱이 이 키를 사용합니다. 다른 키를 사용해 보세요."
   },
+  "compose_windows": {
+    "more_formatting": "추가 서식",
+    "offline": "오프라인",
+    "offline_hint": "보내려면 연결이 필요합니다.",
+    "offline_hint_outbox": "지금 보내는 메일은 보낼편지함에서 기다리다가 다시 온라인이 되면 전송됩니다.",
+    "offline_send_saved": "오프라인 상태입니다. 메시지는 임시보관함에 저장되어 있습니다.",
+    "offline_send_unsaved": "오프라인 상태입니다. 메시지는 여기에 남아 있으며 다시 온라인이 되면 임시보관함에 저장됩니다."
+  },
   "desktopReminders": {
     "generic_title": "알림",
     "snooze": "{count}분 후 다시 알림",
diff --git a/locales/lv/common.json b/locales/lv/common.json
index 19f579b5e..4b822a22c 100644
--- a/locales/lv/common.json
+++ b/locales/lv/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Šie taustiņi jūsu tastatūrā raksta rakstzīmi, kas pārstātu darboties visās lietotnēs. Izmēģiniet citus taustiņus.",
     "reserved": "Šos taustiņus izmanto sistēma vai lielākā daļa lietotņu. Izmēģiniet citus taustiņus."
   },
+  "compose_windows": {
+    "more_formatting": "Vairāk formatēšanas",
+    "offline": "Bezsaistē",
+    "offline_hint": "Sūtīšanai vajadzīgs savienojums.",
+    "offline_hint_outbox": "Ko sūtāt tagad, gaida izsūtnē un tiek nosūtīts, kad atkal esat tiešsaistē.",
+    "offline_send_saved": "Jūs esat bezsaistē. Ziņojums ir saglabāts melnrakstos.",
+    "offline_send_unsaved": "Jūs esat bezsaistē. Ziņojums paliek šeit un tiks saglabāts melnrakstos, kad atkal būsiet tiešsaistē."
+  },
   "desktopReminders": {
     "generic_title": "Atgādinājums",
     "snooze": "Atlikt par {count} min",
diff --git a/locales/mn/common.json b/locales/mn/common.json
index 22bbfaa7e..a0a492b57 100644
--- a/locales/mn/common.json
+++ b/locales/mn/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Эдгээр товч таны гар дээр тэмдэгт бичдэг тул тэр тэмдэгт бүх аппад ажиллахаа болино. Өөр товч туршина уу.",
     "reserved": "Систем эсвэл ихэнх апп эдгээр товчийг ашигладаг. Өөр товч туршина уу."
   },
+  "compose_windows": {
+    "more_formatting": "Бусад хэлбэржүүлэлт",
+    "offline": "Офлайн",
+    "offline_hint": "Илгээхэд холболт хэрэгтэй.",
+    "offline_hint_outbox": "Одоо илгээсэн зүйл гарах хайрцагт хүлээж, онлайн болмогц илгээгдэнэ.",
+    "offline_send_saved": "Та офлайн байна. Мессеж нооргонд хадгалагдсан.",
+    "offline_send_unsaved": "Та офлайн байна. Мессеж энд үлдэж, онлайн болмогц нооргонд хадгалагдана."
+  },
   "desktopReminders": {
     "generic_title": "Сануулга",
     "snooze": "{count} минут хойшлуулах",
diff --git a/locales/nb/common.json b/locales/nb/common.json
index 7d0f99430..64bd1d76f 100644
--- a/locales/nb/common.json
+++ b/locales/nb/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Disse tastene skriver et tegn på tastaturet ditt, og det ville slutte å virke i alle apper. Prøv andre taster.",
     "reserved": "Systemet ditt eller de fleste apper bruker disse tastene. Prøv andre taster."
   },
+  "compose_windows": {
+    "more_formatting": "Mer formatering",
+    "offline": "Frakoblet",
+    "offline_hint": "Du må ha tilkobling for å sende.",
+    "offline_hint_outbox": "Det du sender nå, venter i utboksen og sendes når du er på nett igjen.",
+    "offline_send_saved": "Du er frakoblet. Meldingen er lagret i Utkast.",
+    "offline_send_unsaved": "Du er frakoblet. Meldingen blir her og lagres i Utkast når du er på nett igjen."
+  },
   "desktopReminders": {
     "generic_title": "Påminnelse",
     "snooze": "Utsett {count} min",
diff --git a/locales/nl/common.json b/locales/nl/common.json
index d7634a009..8d98a7a6b 100644
--- a/locales/nl/common.json
+++ b/locales/nl/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Deze toetsen typen een teken op je toetsenbord, en dat zou in geen enkele app meer werken. Probeer andere toetsen.",
     "reserved": "Je systeem of de meeste apps gebruiken deze toetsen. Probeer andere toetsen."
   },
+  "compose_windows": {
+    "more_formatting": "Meer opmaak",
+    "offline": "Offline",
+    "offline_hint": "Voor verzenden is een verbinding nodig.",
+    "offline_hint_outbox": "Wat je nu verstuurt, wacht in Postvak UIT en gaat weg zodra je weer online bent.",
+    "offline_send_saved": "Je bent offline. Het bericht is opgeslagen in Concepten.",
+    "offline_send_unsaved": "Je bent offline. Het bericht blijft hier en wordt in Concepten opgeslagen zodra je weer online bent."
+  },
   "desktopReminders": {
     "generic_title": "Herinnering",
     "snooze": "{count} min uitstellen",
diff --git a/locales/pl/common.json b/locales/pl/common.json
index 8af14a9e8..517637d99 100644
--- a/locales/pl/common.json
+++ b/locales/pl/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Te klawisze wpisują znak na Twojej klawiaturze i przestałby on działać we wszystkich aplikacjach. Wypróbuj inne klawisze.",
     "reserved": "Te klawisze są używane przez system lub większość aplikacji. Wypróbuj inne klawisze."
   },
+  "compose_windows": {
+    "more_formatting": "Więcej formatowania",
+    "offline": "Offline",
+    "offline_hint": "Do wysłania potrzebne jest połączenie.",
+    "offline_hint_outbox": "To, co teraz wyślesz, czeka w skrzynce nadawczej i wyjdzie, gdy wrócisz do sieci.",
+    "offline_send_saved": "Jesteś offline. Wiadomość jest zapisana w Szkicach.",
+    "offline_send_unsaved": "Jesteś offline. Wiadomość zostaje tutaj i zostanie zapisana w Szkicach, gdy wrócisz do sieci."
+  },
   "desktopReminders": {
     "generic_title": "Przypomnienie",
     "snooze": "Odłóż o {count} min",
diff --git a/locales/pt/common.json b/locales/pt/common.json
index 5111a4013..192489a92 100644
--- a/locales/pt/common.json
+++ b/locales/pt/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Estas teclas escrevem um carácter no seu teclado, e ele deixaria de funcionar em todas as aplicações. Experimente outras teclas.",
     "reserved": "O seu sistema ou a maioria das aplicações usam estas teclas. Experimente outras teclas."
   },
+  "compose_windows": {
+    "more_formatting": "Mais formatação",
+    "offline": "Offline",
+    "offline_hint": "Enviar precisa de ligação.",
+    "offline_hint_outbox": "O que enviar agora espera na caixa de saída e é enviado quando voltar a estar online.",
+    "offline_send_saved": "Está offline. A mensagem está guardada em Rascunhos.",
+    "offline_send_unsaved": "Está offline. A mensagem fica aqui e é guardada em Rascunhos quando voltar a estar online."
+  },
   "desktopReminders": {
     "generic_title": "Lembrete",
     "snooze": "Adiar {count} min",
diff --git a/locales/ro/common.json b/locales/ro/common.json
index 733283ce6..fb9a52ef6 100644
--- a/locales/ro/common.json
+++ b/locales/ro/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Aceste taste scriu un caracter pe tastatura ta, iar el n-ar mai funcționa în nicio aplicație. Încearcă alte taste.",
     "reserved": "Sistemul sau majoritatea aplicațiilor folosesc aceste taste. Încearcă alte taste."
   },
+  "compose_windows": {
+    "more_formatting": "Mai multe opțiuni de formatare",
+    "offline": "Offline",
+    "offline_hint": "Pentru trimitere e nevoie de conexiune.",
+    "offline_hint_outbox": "Ce trimiteți acum așteaptă în Mesaje de trimis și pleacă atunci când sunteți din nou online.",
+    "offline_send_saved": "Sunteți offline. Mesajul este salvat în Ciorne.",
+    "offline_send_unsaved": "Sunteți offline. Mesajul rămâne aici și este salvat în Ciorne când sunteți din nou online."
+  },
   "desktopReminders": {
     "generic_title": "Memento",
     "snooze": "Amână {count} min",
diff --git a/locales/ru/common.json b/locales/ru/common.json
index c63313d37..c6f29fd16 100644
--- a/locales/ru/common.json
+++ b/locales/ru/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "На вашей клавиатуре эти клавиши вводят символ, и он перестал бы работать во всех приложениях. Попробуйте другие клавиши.",
     "reserved": "Эти клавиши использует система или большинство приложений. Попробуйте другие клавиши."
   },
+  "compose_windows": {
+    "more_formatting": "Дополнительное форматирование",
+    "offline": "Не в сети",
+    "offline_hint": "Для отправки нужно подключение.",
+    "offline_hint_outbox": "То, что вы отправите сейчас, подождёт в исходящих и уйдёт, когда вы снова будете в сети.",
+    "offline_send_saved": "Вы не в сети. Сообщение сохранено в черновиках.",
+    "offline_send_unsaved": "Вы не в сети. Сообщение останется здесь и сохранится в черновиках, когда вы снова будете в сети."
+  },
   "desktopReminders": {
     "generic_title": "Напоминание",
     "snooze": "Отложить на {count} мин",
diff --git a/locales/sk/common.json b/locales/sk/common.json
index 070aec513..91eaacf94 100644
--- a/locales/sk/common.json
+++ b/locales/sk/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Tieto klávesy na vašej klávesnici píšu znak, ktorý by potom nefungoval v žiadnej aplikácii. Skúste iné klávesy.",
     "reserved": "Tieto klávesy používa systém alebo väčšina aplikácií. Skúste iné klávesy."
   },
+  "compose_windows": {
+    "more_formatting": "Ďalšie formátovanie",
+    "offline": "Offline",
+    "offline_hint": "Na odoslanie treba pripojenie.",
+    "offline_hint_outbox": "Čo teraz odošlete, počká medzi správami na odoslanie a odíde, keď budete znova online.",
+    "offline_send_saved": "Ste offline. Správa je uložená v Konceptoch.",
+    "offline_send_unsaved": "Ste offline. Správa tu zostane a uloží sa do Konceptov, keď budete znova online."
+  },
   "desktopReminders": {
     "generic_title": "Pripomienka",
     "snooze": "Odložiť o {count} min",
diff --git a/locales/th/common.json b/locales/th/common.json
index 7d9dd0b0e..f065a2157 100644
--- a/locales/th/common.json
+++ b/locales/th/common.json
@@ -7117,6 +7117,14 @@
     "types_character": "ปุ่มเหล่านี้พิมพ์อักขระบนแป้นพิมพ์ของคุณ และอักขระนั้นจะใช้ไม่ได้ในทุกแอป ลองใช้ปุ่มอื่น",
     "reserved": "ระบบหรือแอปส่วนใหญ่ใช้ปุ่มเหล่านี้ ลองใช้ปุ่มอื่น"
   },
+  "compose_windows": {
+    "more_formatting": "การจัดรูปแบบเพิ่มเติม",
+    "offline": "ออฟไลน์",
+    "offline_hint": "ต้องเชื่อมต่อจึงจะส่งได้",
+    "offline_hint_outbox": "สิ่งที่คุณส่งตอนนี้จะรออยู่ในกล่องขาออกและถูกส่งเมื่อคุณกลับมาออนไลน์",
+    "offline_send_saved": "คุณออฟไลน์อยู่ ข้อความถูกบันทึกไว้ในจดหมายร่างแล้ว",
+    "offline_send_unsaved": "คุณออฟไลน์อยู่ ข้อความจะอยู่ที่นี่และถูกบันทึกในจดหมายร่างเมื่อคุณกลับมาออนไลน์"
+  },
   "desktopReminders": {
     "generic_title": "การแจ้งเตือน",
     "snooze": "เลื่อน {count} นาที",
diff --git a/locales/tr/common.json b/locales/tr/common.json
index 7cae9a10d..a57478d98 100644
--- a/locales/tr/common.json
+++ b/locales/tr/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "Bu tuşlar klavyenizde bir karakter yazar ve bu karakter hiçbir uygulamada çalışmaz olur. Başka tuşlar deneyin.",
     "reserved": "Bu tuşları sisteminiz veya çoğu uygulama kullanıyor. Başka tuşlar deneyin."
   },
+  "compose_windows": {
+    "more_formatting": "Daha fazla biçimlendirme",
+    "offline": "Çevrimdışı",
+    "offline_hint": "Göndermek için bağlantı gerekir.",
+    "offline_hint_outbox": "Şimdi gönderdikleriniz giden kutusunda bekler ve yeniden çevrimiçi olduğunuzda gönderilir.",
+    "offline_send_saved": "Çevrimdışısınız. İleti Taslaklar'a kaydedildi.",
+    "offline_send_unsaved": "Çevrimdışısınız. İleti burada kalır ve yeniden çevrimiçi olduğunuzda Taslaklar'a kaydedilir."
+  },
   "desktopReminders": {
     "generic_title": "Anımsatıcı",
     "snooze": "{count} dk ertele",
diff --git a/locales/uk/common.json b/locales/uk/common.json
index 2fe8cc2da..78662b5a1 100644
--- a/locales/uk/common.json
+++ b/locales/uk/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "На вашій клавіатурі ці клавіші вводять символ, і він перестав би працювати в усіх застосунках. Спробуйте інші клавіші.",
     "reserved": "Ці клавіші використовує система або більшість застосунків. Спробуйте інші клавіші."
   },
+  "compose_windows": {
+    "more_formatting": "Додаткове форматування",
+    "offline": "Не в мережі",
+    "offline_hint": "Для надсилання потрібне підключення.",
+    "offline_hint_outbox": "Те, що ви надішлете зараз, чекатиме у вихідних і піде, коли ви знову будете в мережі.",
+    "offline_send_saved": "Ви не в мережі. Повідомлення збережено в чернетках.",
+    "offline_send_unsaved": "Ви не в мережі. Повідомлення залишиться тут і збережеться в чернетках, коли ви знову будете в мережі."
+  },
   "desktopReminders": {
     "generic_title": "Нагадування",
     "snooze": "Відкласти на {count} хв",
diff --git a/locales/vi/common.json b/locales/vi/common.json
index b9ffe90df..bcf9b2f50 100644
--- a/locales/vi/common.json
+++ b/locales/vi/common.json
@@ -7121,6 +7121,14 @@
     "types_character": "Các phím này gõ một ký tự trên bàn phím của bạn, và ký tự đó sẽ không dùng được trong mọi ứng dụng. Hãy thử phím khác.",
     "reserved": "Hệ thống hoặc hầu hết ứng dụng dùng các phím này. Hãy thử phím khác."
   },
+  "compose_windows": {
+    "more_formatting": "Thêm định dạng",
+    "offline": "Ngoại tuyến",
+    "offline_hint": "Cần có kết nối để gửi.",
+    "offline_hint_outbox": "Thư bạn gửi bây giờ sẽ chờ trong Hộp thư đi và được gửi khi bạn trực tuyến trở lại.",
+    "offline_send_saved": "Bạn đang ngoại tuyến. Thư đã được lưu trong Bản nháp.",
+    "offline_send_unsaved": "Bạn đang ngoại tuyến. Thư vẫn ở đây và sẽ được lưu vào Bản nháp khi bạn trực tuyến trở lại."
+  },
   "desktopReminders": {
     "generic_title": "Lời nhắc",
     "snooze": "Báo lại sau {count} phút",
diff --git a/locales/zh-TW/common.json b/locales/zh-TW/common.json
index f6a9b6eb3..845487676 100644
--- a/locales/zh-TW/common.json
+++ b/locales/zh-TW/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "這些鍵在您的鍵盤上會輸入一個字元，占用後該字元在所有應用程式中都無法輸入。請試試其他按鍵。",
     "reserved": "系統或大多數應用程式正在使用這些鍵。請試試其他按鍵。"
   },
+  "compose_windows": {
+    "more_formatting": "更多格式",
+    "offline": "離線",
+    "offline_hint": "寄出需要連線。",
+    "offline_hint_outbox": "你現在寄出的郵件會在寄件匣中等待，恢復連線後送出。",
+    "offline_send_saved": "你已離線。郵件已儲存在草稿中。",
+    "offline_send_unsaved": "你已離線。郵件會留在這裡，恢復連線後儲存到草稿。"
+  },
   "desktopReminders": {
     "generic_title": "提醒",
     "snooze": "{count} 分鐘後再提醒",
diff --git a/locales/zh/common.json b/locales/zh/common.json
index e8c040237..12cfc890b 100644
--- a/locales/zh/common.json
+++ b/locales/zh/common.json
@@ -7109,6 +7109,14 @@
     "types_character": "这些键在您的键盘上会输入一个字符，占用后该字符在所有应用中都无法输入。请试试其他按键。",
     "reserved": "系统或大多数应用在使用这些键。请试试其他按键。"
   },
+  "compose_windows": {
+    "more_formatting": "更多格式",
+    "offline": "离线",
+    "offline_hint": "发送需要联网。",
+    "offline_hint_outbox": "你现在发送的邮件会在发件箱中等待，恢复联网后发出。",
+    "offline_send_saved": "你已离线。邮件已保存在草稿中。",
+    "offline_send_unsaved": "你已离线。邮件会留在这里，恢复联网后保存到草稿。"
+  },
   "desktopReminders": {
     "generic_title": "提醒",
     "snooze": "{count} 分钟后再提醒",