From f6ad8a594201aa2d535ff7ec00ef7119f9e36b17 Mon Sep 17 00:00:00 2001
From: Linus Rath <139418639+rathlinus@users.noreply.github.com>
Date: Thu, 17 Sep 2026 22:34:20 +0200
Subject: [PATCH] feat: add per-message HTML/plain-text toggle #1022

---
 .../email/__tests__/compose-format.test.ts    |  86 ++++++
 .../__tests__/composer-format-toggle.test.tsx | 286 ++++++++++++++++++
 components/email/compose-format.ts            | 142 +++++++++
 components/email/email-composer.tsx           | 155 +++++-----
 components/mail/mail-app.tsx                  |   5 +
 locales/ar/common.json                        |   2 +
 locales/ca/common.json                        |   2 +
 locales/cs/common.json                        |   2 +
 locales/da/common.json                        |   2 +
 locales/de/common.json                        |   2 +
 locales/en/common.json                        |   2 +
 locales/es/common.json                        |   2 +
 locales/fa/common.json                        |   2 +
 locales/fr/common.json                        |   2 +
 locales/he/common.json                        |   2 +
 locales/hu/common.json                        |   2 +
 locales/it/common.json                        |   2 +
 locales/ja/common.json                        |   2 +
 locales/ko/common.json                        |   2 +
 locales/lv/common.json                        |   2 +
 locales/mn/common.json                        |   2 +
 locales/nb/common.json                        |   2 +
 locales/nl/common.json                        |   2 +
 locales/pl/common.json                        |   2 +
 locales/pt/common.json                        |   2 +
 locales/ro/common.json                        |   2 +
 locales/ru/common.json                        |   2 +
 locales/sk/common.json                        |   2 +
 locales/tr/common.json                        |   2 +
 locales/uk/common.json                        |   2 +
 locales/zh-TW/common.json                     |   2 +
 locales/zh/common.json                        |   2 +
 32 files changed, 648 insertions(+), 80 deletions(-)
 create mode 100644 components/email/__tests__/compose-format.test.ts
 create mode 100644 components/email/__tests__/composer-format-toggle.test.tsx
 create mode 100644 components/email/compose-format.ts

diff --git a/components/email/__tests__/compose-format.test.ts b/components/email/__tests__/compose-format.test.ts
new file mode 100644
index 000000000..5837505f8
--- /dev/null
+++ b/components/email/__tests__/compose-format.test.ts
@@ -0,0 +1,86 @@
+import { describe, it, expect } from 'vitest';
+import {
+  buildEmbeddedSignatureHtml,
+  htmlComposeBodyToPlainText,
+  plainComposeBodyToHtml,
+  stripEmbeddedSignature,
+} from '../compose-format';
+import { SIGNATURE_BLOCK_MARKER, SIGNATURE_RANGE_MARKER, containsEmbeddedSignature } from '../signature-block';
+import { plainTextBodyHasSignature } from '@/lib/signature-utils';
+
+const identity = { htmlSignature: '<b>Alice</b><br>Acme', textSignature: 'Alice\nAcme' };
+const count = (haystack: string, needle: string) => haystack.split(needle).length - 1;
+
+describe('compose-format (#1022): HTML <-> plain text switch', () => {
+  describe('stripEmbeddedSignature', () => {
+    it('removes the marker-bracketed range and reports it', () => {
+      const html = `<p>Hi</p>${buildEmbeddedSignatureHtml(identity, { embed: true, separator: true })}`;
+      const out = stripEmbeddedSignature(html);
+      expect(out.hadSignature).toBe(true);
+      expect(out.html).toBe('<p>Hi</p>');
+    });
+
+    it('stops before the quote when the end marker is missing', () => {
+      const html = `<p>Hi</p><p ${SIGNATURE_RANGE_MARKER}="separator">-- </p><p>Alice</p><blockquote>original</blockquote>`;
+      const out = stripEmbeddedSignature(html);
+      expect(out.hadSignature).toBe(true);
+      expect(out.html).toBe('<p>Hi</p><blockquote>original</blockquote>');
+    });
+
+    it('leaves a body without markers untouched', () => {
+      expect(stripEmbeddedSignature('<p>Hi</p>')).toEqual({ html: '<p>Hi</p>', hadSignature: false });
+    });
+  });
+
+  describe('htmlComposeBodyToPlainText', () => {
+    it('flattens formatting and carries the signature over as plain text', () => {
+      const html = `<p>Hello <b>there</b></p><p>Second</p>${buildEmbeddedSignatureHtml(identity, { embed: true, separator: true })}`;
+      const text = htmlComposeBodyToPlainText(html, identity, { separator: true });
+      expect(text).toBe('Hello there\n\nSecond\n\n-- \nAlice\nAcme');
+      expect(plainTextBodyHasSignature(text, identity)).toBe(true);
+      expect(count(text, 'Alice')).toBe(1);
+    });
+
+    it('does not invent a signature for a body that had none (below-quote reply)', () => {
+      const text = htmlComposeBodyToPlainText('<p>Thanks</p><blockquote>original</blockquote>', identity, { separator: true });
+      expect(text).toBe('Thanks\n\noriginal');
+      expect(plainTextBodyHasSignature(text, identity)).toBe(false);
+    });
+
+    it('honours the separator setting', () => {
+      const html = `<p>Hi</p>${buildEmbeddedSignatureHtml(identity, { embed: true, separator: false })}`;
+      expect(htmlComposeBodyToPlainText(html, identity, { separator: false })).toBe('Hi\n\nAlice\nAcme');
+    });
+  });
+
+  describe('plainComposeBodyToHtml', () => {
+    it('wraps paragraphs and re-embeds the signature with markers', () => {
+      const html = plainComposeBodyToHtml('Hello\nthere\n\nSecond\n\n-- \nAlice\nAcme', identity, { separator: true });
+      expect(html.startsWith('<p>Hello<br>there</p><p>Second</p>')).toBe(true);
+      expect(containsEmbeddedSignature(html)).toBe(true);
+      expect(count(html, SIGNATURE_BLOCK_MARKER)).toBe(1);
+      expect(html).toContain('<b>Alice</b>');
+      // The plain-text copy is gone - only the embedded HTML one remains.
+      expect(count(html, 'Alice')).toBe(1);
+    });
+
+    it('keeps a body without signature signature-free', () => {
+      const html = plainComposeBodyToHtml('Thanks\n\n> original', identity, { separator: true });
+      expect(html).toBe('<p>Thanks</p><p>&gt; original</p>');
+      expect(containsEmbeddedSignature(html)).toBe(false);
+    });
+
+    it('gives an untouched signature-only body an empty paragraph to type into', () => {
+      const html = plainComposeBodyToHtml('\n\n-- \nAlice\nAcme', identity, { separator: true });
+      expect(html.startsWith('<p></p>')).toBe(true);
+      expect(containsEmbeddedSignature(html)).toBe(true);
+    });
+  });
+
+  it('round-trips a compose body without duplicating or losing the signature', () => {
+    const start = `<p>Draft text</p>${buildEmbeddedSignatureHtml(identity, { embed: true, separator: true })}`;
+    const text = htmlComposeBodyToPlainText(start, identity, { separator: true });
+    const back = plainComposeBodyToHtml(text, identity, { separator: true });
+    expect(back).toBe(start);
+  });
+});
diff --git a/components/email/__tests__/composer-format-toggle.test.tsx b/components/email/__tests__/composer-format-toggle.test.tsx
new file mode 100644
index 000000000..bf91e1886
--- /dev/null
+++ b/components/email/__tests__/composer-format-toggle.test.tsx
@@ -0,0 +1,286 @@
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import React from 'react';
+import { EmailComposer } from '../email-composer';
+import { useSettingsStore } from '@/stores/settings-store';
+import { SIGNATURE_BLOCK_MARKER } from '../signature-block';
+
+// ─── Heavy component mocks (mirrors composer-reopened-draft-signature.test.tsx) ─
+
+vi.mock('@/components/email/rich-text-editor', () => ({
+  RichTextEditor: () => React.createElement('div', { 'data-testid': 'rich-text-editor' }),
+}));
+
+vi.mock('@/components/plugins/plugin-slot', () => ({ PluginSlot: () => 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 }),
+}));
+
+// ─── Store mocks ──────────────────────────────────────────────────────────────
+
+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', htmlSignature: '<b>Alice</b>', textSignature: 'Alice' },
+    ] as Array<Record<string, unknown>>,
+    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,
+    // The default position: replies/forwards get the signature appended at
+    // send time rather than embedded above the quote.
+    signaturePosition: 'below_quote',
+    signatureSeparatorEnabled: true,
+    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 };
+});
+
+// ─── Misc dependency mocks ────────────────────────────────────────────────────
+
+vi.mock('@/stores/toast-store', () => ({
+  toast: { info: () => {}, error: () => {}, success: () => {} },
+}));
+
+vi.mock('@/lib/plugin-hooks', () => ({
+  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 },
+    onComposeSend: { intercept: async () => true },
+    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,
+  sanitizeSignatureHtmlForDisplay: (v: string) => v,
+  sanitizeEmailHtml: (v: string) => v,
+  sanitizePluginBodyHtml: (v: string) => v,
+  escapeHtml: (v: string) => v,
+  parseHtmlSafely: (html: string) => new DOMParser().parseFromString(html, 'text/html'),
+}));
+
+vi.mock('@/lib/email-threading', () => ({
+  computeReplyThreadingHeaders: () => ({ inReplyTo: [], references: [] }),
+}));
+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 }));
+
+// ─── Tests ────────────────────────────────────────────────────────────────────
+
+/**
+ * #1022: the HTML / plain-text choice used to live only in settings. The
+ * composer toolbar now carries a per-message toggle. Switching converts the
+ * body in place and keeps the signature invariant (exactly one copy, in the
+ * target format) that the send path relies on.
+ */
+
+const DRAFT = {
+  to: 'bob@example.com',
+  cc: '',
+  bcc: '',
+  subject: 'Hello',
+  body: '<p>Draft <b>text</b></p>',
+  showCc: false,
+  showBcc: false,
+  selectedIdentityId: 'id-me',
+  subAddressTag: '',
+  mode: 'compose' as const,
+  draftId: null,
+};
+
+const toggle = () => screen.getByTestId('composer-format-toggle') as HTMLButtonElement;
+const sendButton = () => screen.getAllByTestId('composer-send')[0] as HTMLButtonElement;
+const textarea = () => document.querySelector('textarea') as HTMLTextAreaElement | null;
+const countOf = (haystack: string, needle: string) => haystack.split(needle).length - 1;
+
+async function send(onSend: ReturnType<typeof vi.fn>) {
+  fireEvent.click(sendButton());
+  await waitFor(() => expect(onSend).toHaveBeenCalledTimes(1));
+  return onSend.mock.calls[0][0] as { body: string; htmlBody?: string };
+}
+
+describe('composer HTML / plain-text toggle (#1022)', () => {
+  afterEach(() => {
+    useSettingsStore.setState({ plainTextMode: false });
+    vi.clearAllMocks();
+  });
+
+  it('starts in the rich-text editor and switches to a plain-text textarea', () => {
+    render(<EmailComposer initialData={DRAFT} />);
+    expect(screen.getByTestId('rich-text-editor')).toBeInTheDocument();
+    expect(textarea()).toBeNull();
+    expect(toggle()).toHaveAttribute('aria-pressed', 'false');
+    expect(toggle()).toHaveAttribute('title', 'format_plain_text');
+
+    fireEvent.click(toggle());
+
+    expect(screen.queryByTestId('rich-text-editor')).not.toBeInTheDocument();
+    expect(toggle()).toHaveAttribute('aria-pressed', 'true');
+    expect(toggle()).toHaveAttribute('title', 'format_rich_text');
+    // Formatting flattened, signature carried over as plain text - once.
+    expect(textarea()!.value).toBe('Draft text\n\n-- \nAlice');
+  });
+
+  it('sends text/plain only after switching, with exactly one signature', async () => {
+    const onSend = vi.fn();
+    render(<EmailComposer initialData={DRAFT} onSend={onSend} />);
+    fireEvent.click(toggle());
+
+    const sent = await send(onSend);
+    expect(sent.htmlBody).toBeUndefined();
+    expect(sent.body).toBe('Draft text\n\n-- \nAlice');
+    expect(countOf(sent.body, 'Alice')).toBe(1);
+  });
+
+  it('switches back to HTML and sends an embedded signature exactly once', async () => {
+    const onSend = vi.fn();
+    render(<EmailComposer initialData={DRAFT} onSend={onSend} />);
+    fireEvent.click(toggle());
+    fireEvent.change(textarea()!, { target: { value: 'Edited\n\nSecond\n\n-- \nAlice' } });
+    fireEvent.click(toggle());
+
+    expect(screen.getByTestId('rich-text-editor')).toBeInTheDocument();
+    expect(textarea()).toBeNull();
+
+    const sent = await send(onSend);
+    expect(sent.htmlBody).toContain('<p>Edited</p><p>Second</p>');
+    expect(countOf(sent.htmlBody!, SIGNATURE_BLOCK_MARKER)).toBe(1);
+    expect(countOf(sent.htmlBody!, '<b>Alice</b>')).toBe(1);
+    expect(countOf(sent.body, 'Alice')).toBe(1);
+  });
+
+  it('honours the "plain text only" setting as the default and still lets the user switch', () => {
+    useSettingsStore.setState({ plainTextMode: true });
+    render(<EmailComposer initialData={{ ...DRAFT, body: 'Plain draft' }} />);
+    expect(textarea()).not.toBeNull();
+    expect(toggle()).toHaveAttribute('aria-pressed', 'true');
+
+    fireEvent.click(toggle());
+    expect(screen.getByTestId('rich-text-editor')).toBeInTheDocument();
+  });
+
+  it('re-opens a draft in the format it was written in', () => {
+    render(<EmailComposer initialData={{ ...DRAFT, body: 'Plain draft', plainTextMode: true }} />);
+    expect(textarea()).not.toBeNull();
+    expect(textarea()!.value).toContain('Plain draft');
+  });
+
+  it('stashes the chosen format with the draft on unmount', () => {
+    const onSaveState = vi.fn();
+    const { unmount } = render(<EmailComposer initialData={DRAFT} onSaveState={onSaveState} />);
+    fireEvent.click(toggle());
+    fireEvent.change(textarea()!, { target: { value: 'changed' } });
+    unmount();
+    expect(onSaveState).toHaveBeenCalledTimes(1);
+    expect(onSaveState.mock.calls[0][0]).toMatchObject({ plainTextMode: true, body: 'changed' });
+  });
+});
diff --git a/components/email/compose-format.ts b/components/email/compose-format.ts
new file mode 100644
index 000000000..4d4e918a6
--- /dev/null
+++ b/components/email/compose-format.ts
@@ -0,0 +1,142 @@
+import { sanitizeSignatureHtml } from "@/lib/email-sanitization";
+import { htmlToPlainText } from "@/lib/html-to-text";
+import { plainTextToComposerBody } from "@/lib/email-composer-utils";
+import {
+  appendPlainTextSignature,
+  plainTextBodyHasSignature,
+  plainTextBodyWithoutSignature,
+} from "@/lib/signature-utils";
+import { buildSignatureBlock, SIGNATURE_RANGE_MARKER } from "@/components/email/signature-block";
+
+/**
+ * Helpers for the composer's per-message HTML <-> plain-text switch (#1022).
+ *
+ * Both directions preserve the one invariant the send and draft-save paths
+ * rely on: whether the body *carries* the signature. An HTML body carries it
+ * as a marker-bracketed range (`containsEmbeddedSignature`), a plain-text
+ * body by ending with the signature text (`plainTextBodyHasSignature`). The
+ * converters strip the signature in the source format and re-append it in
+ * the target format, so a switch never produces a doubled or lost signature.
+ */
+
+export type SignatureIdentityLike = {
+  htmlSignature?: string;
+  textSignature?: string;
+} | null | undefined;
+
+// Render the embedded signature. Bracketed with `data-signature-block` marker
+// paragraphs so we can swap the inner content when the user switches identity
+// without losing the surrounding draft or quoted message. The markers are
+// preserved through TipTap by the StyledParagraph extension. The HTML
+// signature itself is wrapped in a SignatureBlock atom node so its inline
+// styling survives the editor (see signature-block.ts) instead of being
+// flattened by the schema.
+export function buildEmbeddedSignatureHtml(
+  identity: SignatureIdentityLike,
+  options: { embed: boolean; separator: boolean }
+): string {
+  if (!options.embed) return '';
+  const startMarker = options.separator
+    ? `<p ${SIGNATURE_RANGE_MARKER}="separator">-- </p>`
+    : `<p ${SIGNATURE_RANGE_MARKER}="start"></p>`;
+  const endMarker = `<p ${SIGNATURE_RANGE_MARKER}="end"></p>`;
+  if (identity?.htmlSignature) {
+    return `${startMarker}${buildSignatureBlock(sanitizeSignatureHtml(identity.htmlSignature))}${endMarker}`;
+  }
+  if (identity?.textSignature) {
+    const escaped = identity.textSignature
+      .replace(/&/g, '&amp;')
+      .replace(/</g, '&lt;')
+      .replace(/>/g, '&gt;')
+      .replace(/\n/g, '<br>');
+    return `${startMarker}<p>${escaped}</p>${endMarker}`;
+  }
+  return '';
+}
+
+function isQuoteBoundary(node: Node | null): boolean {
+  if (!node || node.nodeType !== 1) return false;
+  const el = node as Element;
+  return el.tagName === 'BLOCKQUOTE' || el.hasAttribute('data-quoted-html');
+}
+
+/**
+ * Remove the embedded signature range [start/separator marker … end marker]
+ * from a parsed body. Without an end marker the removal stops before the next
+ * quote boundary (a legacy <blockquote> or the QuotedHtml island) so it never
+ * eats into the quoted message. Returns the removed nodes' former position so
+ * a caller can splice a replacement in, or null when the body has no range.
+ */
+export function removeSignatureRange(
+  doc: Document,
+): { parent: Node; insertBefore: Node | null } | null {
+  const startEl = doc.querySelector(
+    `[${SIGNATURE_RANGE_MARKER}="separator"], [${SIGNATURE_RANGE_MARKER}="start"]`
+  );
+  if (!startEl) return null;
+  const parent = startEl.parentNode;
+  if (!parent) return null;
+  const endEl = doc.querySelector(`[${SIGNATURE_RANGE_MARKER}="end"]`);
+  const removeUntil = endEl && endEl.parentNode === parent ? endEl : null;
+
+  const toRemove: Node[] = [];
+  let cursor: Node | null = startEl;
+  while (cursor) {
+    toRemove.push(cursor);
+    if (cursor === removeUntil) break;
+    const next: Node | null = cursor.nextSibling;
+    if (!removeUntil && isQuoteBoundary(next)) break;
+    cursor = next;
+  }
+  const insertBefore = toRemove[toRemove.length - 1]?.nextSibling ?? null;
+  toRemove.forEach((node) => parent.removeChild(node));
+  return { parent, insertBefore };
+}
+
+/**
+ * The HTML body with its embedded signature range removed, plus whether one
+ * was there. A bare signature atom without range markers (a body whose marker
+ * paragraphs were dropped) is left in place - it has no defined extent.
+ */
+export function stripEmbeddedSignature(html: string): { html: string; hadSignature: boolean } {
+  if (!html.includes(SIGNATURE_RANGE_MARKER)) return { html, hadSignature: false };
+  const doc = new DOMParser().parseFromString(html, 'text/html');
+  const removed = removeSignatureRange(doc);
+  if (!removed) return { html, hadSignature: false };
+  return { html: doc.body.innerHTML, hadSignature: true };
+}
+
+/**
+ * Convert the rich-text editor's body to a plain-text body. Formatting is
+ * dropped (that is the point of plain text); an embedded signature comes back
+ * as the identity's plain-text signature so the body still "carries" it.
+ */
+export function htmlComposeBodyToPlainText(
+  html: string,
+  identity: SignatureIdentityLike,
+  options: { separator: boolean },
+): string {
+  const stripped = stripEmbeddedSignature(html);
+  const text = htmlToPlainText(stripped.html, { paragraphSpacing: true });
+  if (!stripped.hadSignature) return text;
+  return appendPlainTextSignature(text, identity, { separator: options.separator });
+}
+
+/**
+ * Convert a plain-text body to editor HTML: paragraphs per blank line, <br>
+ * per newline. A trailing plain-text signature is swapped for the embedded
+ * (marker-bracketed) HTML signature so identity switches and the send path
+ * keep working as in a body that started out as HTML.
+ */
+export function plainComposeBodyToHtml(
+  text: string,
+  identity: SignatureIdentityLike,
+  options: { separator: boolean },
+): string {
+  const hadSignature = plainTextBodyHasSignature(text, identity);
+  const userText = hadSignature ? plainTextBodyWithoutSignature(text, identity) : text;
+  const html = plainTextToComposerBody(userText);
+  if (!hadSignature) return html;
+  const embedded = buildEmbeddedSignatureHtml(identity, { embed: true, separator: options.separator });
+  return `${html || '<p></p>'}${embedded}`;
+}
diff --git a/components/email/email-composer.tsx b/components/email/email-composer.tsx
index 04d63e49a..899f62d01 100644
--- a/components/email/email-composer.tsx
+++ b/components/email/email-composer.tsx
@@ -5,7 +5,7 @@ import { useFocusTrap } from "@/hooks/use-focus-trap";
 import { useTranslations } from "next-intl";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
-import { X, Paperclip, Send, Save, Check, Loader2, AlertCircle, FileText, BookmarkPlus, CalendarClock, ChevronDown, MailCheck, Search, Users, PackageCheck, LockKeyhole } from "lucide-react";
+import { X, Paperclip, Send, Save, Check, Loader2, AlertCircle, FileText, BookmarkPlus, CalendarClock, ChevronDown, MailCheck, Search, Users, PackageCheck, LockKeyhole, Type } from "lucide-react";
 import { cn, formatFileSize, formatDateTime, generateUUID } from "@/lib/utils";
 import { debug } from "@/lib/debug";
 import { toast } from "@/stores/toast-store";
@@ -16,7 +16,13 @@ import { buildReplySubject, buildForwardSubject } from "@/lib/subject-prefix";
 import { isFilePreviewable } from "@/lib/file-preview";
 import { isEditableEventTarget } from "@/lib/keyboard";
 import { buildQuotedHtmlBlock, serializeEditorContent } from "@/components/email/quoted-html";
-import { buildSignatureBlock, containsEmbeddedSignature, SIGNATURE_RANGE_MARKER } from "@/components/email/signature-block";
+import { containsEmbeddedSignature } from "@/components/email/signature-block";
+import {
+  buildEmbeddedSignatureHtml,
+  htmlComposeBodyToPlainText,
+  plainComposeBodyToHtml,
+  removeSignatureRange,
+} from "@/components/email/compose-format";
 import { emailHooks, contactHooks, isExternalAttachmentResult } from "@/lib/plugin-hooks";
 import { onUploadProgress } from "@/lib/upload-progress";
 import type { AlmostSavedDraft, OutgoingEmail, PluginAttachmentUpload, RecipientSuggestion } from "@/lib/plugin-types";
@@ -129,6 +135,12 @@ export interface ComposerDraftData {
   fromOverrideEmail?: string;
   fromOverrideName?: string;
   fromOverrideEnabled?: boolean;
+  /**
+   * Format the body is in. Absent, the "plain text only" setting decides -
+   * set for a stashed compose or a re-opened draft so it comes back in the
+   * format it was written in (#1022).
+   */
+  plainTextMode?: boolean;
 }
 
 interface EmailComposerProps {
@@ -244,41 +256,6 @@ type ComposerAttachment = {
   fromDraftPart?: boolean;
 };
 
-type SignatureIdentityLike = {
-  htmlSignature?: string;
-  textSignature?: string;
-} | null | undefined;
-
-// Render the embedded signature. Bracketed with `data-signature-block` marker
-// paragraphs so we can swap the inner content when the user switches identity
-// without losing the surrounding draft or quoted message. The markers are
-// preserved through TipTap by the StyledParagraph extension. The HTML
-// signature itself is wrapped in a SignatureBlock atom node so its inline
-// styling survives the editor (see signature-block.ts) instead of being
-// flattened by the schema.
-function buildEmbeddedSignatureHtml(
-  identity: SignatureIdentityLike,
-  options: { embed: boolean; separator: boolean }
-): string {
-  if (!options.embed) return '';
-  const startMarker = options.separator
-    ? `<p ${SIGNATURE_RANGE_MARKER}="separator">-- </p>`
-    : `<p ${SIGNATURE_RANGE_MARKER}="start"></p>`;
-  const endMarker = `<p ${SIGNATURE_RANGE_MARKER}="end"></p>`;
-  if (identity?.htmlSignature) {
-    return `${startMarker}${buildSignatureBlock(sanitizeSignatureHtml(identity.htmlSignature))}${endMarker}`;
-  }
-  if (identity?.textSignature) {
-    const escaped = identity.textSignature
-      .replace(/&/g, '&amp;')
-      .replace(/</g, '&lt;')
-      .replace(/>/g, '&gt;')
-      .replace(/\n/g, '<br>');
-    return `${startMarker}<p>${escaped}</p>${endMarker}`;
-  }
-  return '';
-}
-
 function formatLocalDateTimeInput(date: Date): string {
   const pad = (value: number) => String(value).padStart(2, '0');
   return `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())}T${pad(date.getHours())}:${pad(date.getMinutes())}`;
@@ -309,7 +286,13 @@ export function EmailComposer({
   const tCommon = useTranslations('common');
   const tQuote = useTranslations('quote_header');
   const timeFormat = useSettingsStore((state) => state.timeFormat);
-  const plainTextMode = useSettingsStore((state) => state.plainTextMode);
+  const plainTextModeDefault = useSettingsStore((state) => state.plainTextMode);
+  // Per-message format (#1022). Seeded from the "plain text only" setting -
+  // or the format a re-opened / stashed draft was written in - and switchable
+  // from the toolbar for just this message.
+  const [plainTextMode, setPlainTextMode] = useState<boolean>(
+    () => initialData?.plainTextMode ?? plainTextModeDefault
+  );
   const subAddressDelimiter = useSettingsStore((state) => state.subAddressDelimiter);
   const autoSelectReplyIdentity = useSettingsStore((state) => state.autoSelectReplyIdentity);
   const replyIdentityMatch = useSettingsStore((state) => state.replyIdentityMatch);
@@ -747,50 +730,22 @@ export function EmailComposer({
     // body isn't lost during the signature splice + setContent round-trip.
     const currentHtml = serializeEditorContent(editor);
     const doc = new DOMParser().parseFromString(currentHtml, 'text/html');
-    const startEl = doc.querySelector(
-      `[${SIGNATURE_RANGE_MARKER}="separator"], [${SIGNATURE_RANGE_MARKER}="start"]`
-    );
-    if (!startEl) return;
-    const endEl = doc.querySelector(`[${SIGNATURE_RANGE_MARKER}="end"]`);
-
     const newSignature = buildEmbeddedSignatureHtml(signatureIdentity, {
       embed: true,
       separator: signatureSeparatorEnabled,
     });
     if (!newSignature) return;
 
-    // Build a temporary container holding the replacement nodes so we can
-    // splice them in without re-serializing/parsing twice.
+    // Remove the existing signature range (bounded so it never eats into the
+    // quoted body - see removeSignatureRange) and splice the new one in at the
+    // same position, without re-serializing/parsing twice.
+    const removed = removeSignatureRange(doc);
+    if (!removed) return;
     const replacementHost = doc.createElement('div');
     replacementHost.innerHTML = newSignature;
-    const replacementNodes = Array.from(replacementHost.childNodes);
-
-    const parent = startEl.parentNode;
-    if (!parent) return;
-
-    // Remove the existing signature range [startEl … endEl] inclusive, or
-    // from startEl to the next quote boundary if no end marker is present.
-    // The quote boundary is either a legacy <blockquote> or the QuotedHtml
-    // island wrapper (<div data-quoted-html>) - stop before either so the
-    // signature splice never eats into the quoted body.
-    const removeUntil = endEl && endEl.parentNode === parent ? endEl : null;
-    const isQuoteBoundary = (n: Node | null): boolean => {
-      if (!n || n.nodeType !== 1) return false;
-      const el = n as Element;
-      return el.tagName === 'BLOCKQUOTE' || el.hasAttribute('data-quoted-html');
-    };
-    const toRemove: Node[] = [];
-    let cursor: Node | null = startEl;
-    while (cursor) {
-      toRemove.push(cursor);
-      if (cursor === removeUntil) break;
-      const next: Node | null = cursor.nextSibling;
-      if (!removeUntil && isQuoteBoundary(next)) break;
-      cursor = next;
-    }
-    const insertBefore = toRemove[toRemove.length - 1]?.nextSibling ?? null;
-    toRemove.forEach((node) => parent.removeChild(node));
-    replacementNodes.forEach((node) => parent.insertBefore(node, insertBefore));
+    Array.from(replacementHost.childNodes).forEach((node) =>
+      removed.parent.insertBefore(node, removed.insertBefore)
+    );
 
     const nextHtml = doc.body.innerHTML;
     if (nextHtml !== currentHtml) {
@@ -1102,8 +1057,8 @@ export function EmailComposer({
     }));
 
   // Keep a ref to current state for the unmount save
-  const stateRef = useRef({ to: toStr, cc: ccStr, bcc: bccStr, subject, body, showCc, showBcc, selectedIdentityId, subAddressTag, draftId, fromOverrideEnabled, fromOverrideEmail, fromOverrideName, attachments: snapshotAttachments() });
-  stateRef.current = { to: toStr, cc: ccStr, bcc: bccStr, subject, body, showCc, showBcc, selectedIdentityId, subAddressTag, draftId, fromOverrideEnabled, fromOverrideEmail, fromOverrideName, attachments: snapshotAttachments() };
+  const stateRef = useRef({ to: toStr, cc: ccStr, bcc: bccStr, subject, body, showCc, showBcc, selectedIdentityId, subAddressTag, draftId, fromOverrideEnabled, fromOverrideEmail, fromOverrideName, attachments: snapshotAttachments(), plainTextMode });
+  stateRef.current = { to: toStr, cc: ccStr, bcc: bccStr, subject, body, showCc, showBcc, selectedIdentityId, subAddressTag, draftId, fromOverrideEnabled, fromOverrideEmail, fromOverrideName, attachments: snapshotAttachments(), plainTextMode };
 
   // Track initial values for dirty detection (captured once on first render)
   const initialValuesRef = useRef({ to: toStr, cc: ccStr, bcc: bccStr, subject, body, attachmentCount: attachments.length });
@@ -1192,6 +1147,31 @@ export function EmailComposer({
     }
   }, [plainTextMode]);
 
+  // Switch this one message between rich text and plain text (#1022). The
+  // body is converted in place and the embedded signature survives in the
+  // target format (compose-format.ts). Formatting is dropped going to plain
+  // text - that is what plain text means - and does not come back on a
+  // second switch.
+  const togglePlainTextMode = useCallback(() => {
+    const separator = signatureSeparatorEnabled;
+    if (plainTextMode) {
+      setBody((prev) => plainComposeBodyToHtml(prev, signatureIdentity, { separator }));
+      setPlainTextMode(false);
+      return;
+    }
+    // serializeEditorContent (not the React `body` mirror) so a QuotedHtml
+    // island's verbatim body is what gets converted. The editor unmounts with
+    // the switch - drop the ref so nothing talks to a destroyed instance.
+    const editor = editorRef.current;
+    const html = editor && !editor.isDestroyed ? serializeEditorContent(editor) : body;
+    editorRef.current = null;
+    setBody(htmlComposeBodyToPlainText(html, signatureIdentity, { separator }));
+    setPlainTextMode(true);
+    // Keyed on the signature fields, not the identity object (see the
+    // signature effects above for the same rationale).
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [plainTextMode, body, signatureIdentity?.htmlSignature, signatureIdentity?.textSignature, signatureSeparatorEnabled]);
+
   // Move a chip from one recipient field to another. `toIndex`, when given,
   // inserts at that position in the destination (drag-and-drop reordering,
   // #593); omitted, it appends (e.g. dropping onto a hidden Cc/Bcc button).
@@ -2390,7 +2370,7 @@ export function EmailComposer({
       setScheduleValue('');
       setScheduleError('');
       // Clear ref so unmount effect doesn't re-save
-      stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [] };
+      stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [], plainTextMode };
     } catch (err) {
       debug.error('Failed to send email:', err);
       // A timeout is not a clean failure: the submission may have reached the
@@ -2449,7 +2429,7 @@ export function EmailComposer({
     if (saveTimeoutRef.current) {
       clearTimeout(saveTimeoutRef.current);
     }
-    stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [] };
+    stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [], plainTextMode };
     emitClose();
   };
 
@@ -2474,7 +2454,7 @@ export function EmailComposer({
         toast.error(t('save_failed'));
         explicitCloseRef.current = false;
       } else {
-        stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [] };
+        stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [], plainTextMode };
       }
     } finally {
       emitClose();
@@ -2491,7 +2471,7 @@ export function EmailComposer({
     if (draftId && onDiscardDraft) {
       onDiscardDraft(draftId);
     }
-    stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [] };
+    stateRef.current = { to: '', cc: '', bcc: '', subject: '', body: '', showCc: false, showBcc: false, selectedIdentityId: null, subAddressTag: '', draftId: null, fromOverrideEnabled: false, fromOverrideEmail: '', fromOverrideName: '', attachments: [], plainTextMode };
     emitClose();
   };
 
@@ -3109,6 +3089,21 @@ export function EmailComposer({
             >
               <Paperclip className="w-4 h-4" />
             </Button>
+            <Button
+              variant="ghost"
+              size="icon"
+              onClick={togglePlainTextMode}
+              className={cn(
+                "h-9 w-9",
+                plainTextMode && "bg-muted text-foreground hover:bg-muted"
+              )}
+              title={plainTextMode ? t('format_rich_text') : t('format_plain_text')}
+              aria-label={plainTextMode ? t('format_rich_text') : t('format_plain_text')}
+              aria-pressed={plainTextMode}
+              data-testid="composer-format-toggle"
+            >
+              <Type className="w-4 h-4" />
+            </Button>
             {templatesEnabled && <>
               <Button
                 variant="ghost"
diff --git a/components/mail/mail-app.tsx b/components/mail/mail-app.tsx
index e37920a06..e79a8fe34 100644
--- a/components/mail/mail-app.tsx
+++ b/components/mail/mail-app.tsx
@@ -1922,6 +1922,11 @@ export function MailApp({ linkSegments }: MailAppProps = {}) {
       bcc: draft.bcc?.map(a => a.email).filter(Boolean).join(', ') || '',
       subject: draft.subject || '',
       body: htmlBody || bodyText,
+      // Re-open in the format the draft was written in: a text-only draft
+      // used to land raw in the rich-text editor (newlines collapsed) and an
+      // HTML draft raw in the plain-text textarea. Empty draft: the setting
+      // decides (#1022).
+      plainTextMode: htmlBody != null ? false : bodyText ? true : undefined,
       showCc: (draft.cc?.length || 0) > 0,
       showBcc: (draft.bcc?.length || 0) > 0,
       selectedIdentityId: matchedIdentityId,
diff --git a/locales/ar/common.json b/locales/ar/common.json
index 2e2a903d1..6fbb47655 100644
--- a/locales/ar/common.json
+++ b/locales/ar/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "طلب إيصال قراءة",
     "dsn_on": "تم طلب إشعار التسليم (انقر للتعطيل)",
     "dsn_off": "طلب إشعار بالتسليم",
+    "format_plain_text": "التبديل إلى نص عادي",
+    "format_rich_text": "التبديل إلى نص منسق (HTML)",
     "require_tls_on": "التسليم المشفّر مطلوب (انقر للتعطيل)",
     "require_tls_off": "اشتراط التسليم المشفّر (TLS)",
     "new_message": "رسالة جديدة",
diff --git a/locales/ca/common.json b/locales/ca/common.json
index a42b15af6..3af898a14 100644
--- a/locales/ca/common.json
+++ b/locales/ca/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Sol·licita una confirmació de lectura",
     "dsn_on": "Notificació de lliurament sol·licitada (fes clic per desactivar)",
     "dsn_off": "Sol·licita una notificació de lliurament",
+    "format_plain_text": "Canvia a text sense format",
+    "format_rich_text": "Canvia a text enriquit (HTML)",
     "require_tls_on": "Lliurament xifrat obligatori (fes clic per desactivar)",
     "require_tls_off": "Exigeix lliurament xifrat (TLS)",
     "new_message": "Missatge nou",
diff --git a/locales/cs/common.json b/locales/cs/common.json
index 22606460c..2f8a7925e 100644
--- a/locales/cs/common.json
+++ b/locales/cs/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Vyžádat potvrzení o přečtení",
     "dsn_on": "Oznámení o doručení vyžádáno (kliknutím vypnete)",
     "dsn_off": "Vyžádat oznámení o doručení",
+    "format_plain_text": "Přepnout na prostý text",
+    "format_rich_text": "Přepnout na formátovaný text (HTML)",
     "require_tls_on": "Šifrované doručení vyžadováno (kliknutím vypnete)",
     "require_tls_off": "Vyžadovat šifrované doručení (TLS)",
     "new_message": "Nová zpráva",
diff --git a/locales/da/common.json b/locales/da/common.json
index eefb71860..b9e72cc05 100644
--- a/locales/da/common.json
+++ b/locales/da/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Anmod om læsekvittering",
     "dsn_on": "Leveringsbesked anmodet (klik for at slå fra)",
     "dsn_off": "Anmod om leveringsbesked",
+    "format_plain_text": "Skift til ren tekst",
+    "format_rich_text": "Skift til formateret tekst (HTML)",
     "require_tls_on": "Krypteret levering påkrævet (klik for at slå fra)",
     "require_tls_off": "Kræv krypteret levering (TLS)",
     "new_message": "Ny besked",
diff --git a/locales/de/common.json b/locales/de/common.json
index 78e0d750d..f05ba7afe 100644
--- a/locales/de/common.json
+++ b/locales/de/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Lesebestätigung anfordern",
     "dsn_on": "Zustellbenachrichtigung angefordert (zum Deaktivieren klicken)",
     "dsn_off": "Zustellbenachrichtigung anfordern",
+    "format_plain_text": "Zu Nur-Text wechseln",
+    "format_rich_text": "Zu formatiertem Text (HTML) wechseln",
     "require_tls_on": "Verschlüsselte Zustellung erforderlich (zum Deaktivieren klicken)",
     "require_tls_off": "Verschlüsselte Zustellung verlangen (TLS)",
     "new_message": "Neue Nachricht",
diff --git a/locales/en/common.json b/locales/en/common.json
index f030b883d..0e22473c8 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Request a read receipt",
     "dsn_on": "Delivery notification requested (click to disable)",
     "dsn_off": "Request a delivery notification",
+    "format_plain_text": "Switch to plain text",
+    "format_rich_text": "Switch to rich text (HTML)",
     "require_tls_on": "Encrypted delivery required (click to disable)",
     "require_tls_off": "Require encrypted delivery (TLS)",
     "new_message": "New Message",
diff --git a/locales/es/common.json b/locales/es/common.json
index 4b3bf0975..d5b41e1f4 100644
--- a/locales/es/common.json
+++ b/locales/es/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Solicitar confirmación de lectura",
     "dsn_on": "Notificación de entrega solicitada (clic para desactivar)",
     "dsn_off": "Solicitar notificación de entrega",
+    "format_plain_text": "Cambiar a texto sin formato",
+    "format_rich_text": "Cambiar a texto enriquecido (HTML)",
     "require_tls_on": "Entrega cifrada obligatoria (clic para desactivar)",
     "require_tls_off": "Exigir entrega cifrada (TLS)",
     "new_message": "Nuevo Mensaje",
diff --git a/locales/fa/common.json b/locales/fa/common.json
index fa209eca5..690c9e0f0 100644
--- a/locales/fa/common.json
+++ b/locales/fa/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "درخواست تأیید خواندن",
     "dsn_on": "اعلان تحویل درخواست شد (برای غیرفعال کردن کلیک کنید)",
     "dsn_off": "درخواست اعلان تحویل",
+    "format_plain_text": "تغییر به متن ساده",
+    "format_rich_text": "تغییر به متن غنی (HTML)",
     "require_tls_on": "تحویل رمزگذاری‌شده الزامی است (برای غیرفعال کردن کلیک کنید)",
     "require_tls_off": "الزام تحویل رمزگذاری‌شده (TLS)",
     "new_message": "پیام جدید",
diff --git a/locales/fr/common.json b/locales/fr/common.json
index 0d716b4e0..fcf27a3d8 100644
--- a/locales/fr/common.json
+++ b/locales/fr/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Demander un accusé de lecture",
     "dsn_on": "Notification de remise demandée (cliquer pour désactiver)",
     "dsn_off": "Demander une notification de remise",
+    "format_plain_text": "Passer en texte brut",
+    "format_rich_text": "Passer en texte enrichi (HTML)",
     "require_tls_on": "Remise chiffrée exigée (cliquer pour désactiver)",
     "require_tls_off": "Exiger une remise chiffrée (TLS)",
     "new_message": "Nouveau message",
diff --git a/locales/he/common.json b/locales/he/common.json
index 24c16a054..00886598f 100644
--- a/locales/he/common.json
+++ b/locales/he/common.json
@@ -623,6 +623,8 @@
     "read_receipt_off": "בקש קבלת דואר",
     "dsn_on": "התבקש אישור מסירה (לחצו לביטול)",
     "dsn_off": "בקשת אישור מסירה",
+    "format_plain_text": "מעבר לטקסט רגיל",
+    "format_rich_text": "מעבר לטקסט עשיר (HTML)",
     "require_tls_on": "נדרשת מסירה מוצפנת (לחצו לביטול)",
     "require_tls_off": "דרישת מסירה מוצפנת (TLS)",
     "attach_photos": "תמונות וסרטונים",
diff --git a/locales/hu/common.json b/locales/hu/common.json
index fafdc34be..b40386470 100644
--- a/locales/hu/common.json
+++ b/locales/hu/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Olvasási visszaigazolás kérése",
     "dsn_on": "Kézbesítési értesítés kérve (kattints a kikapcsoláshoz)",
     "dsn_off": "Kézbesítési értesítés kérése",
+    "format_plain_text": "Váltás egyszerű szövegre",
+    "format_rich_text": "Váltás formázott szövegre (HTML)",
     "require_tls_on": "Titkosított kézbesítés kötelező (kattints a kikapcsoláshoz)",
     "require_tls_off": "Titkosított kézbesítés megkövetelése (TLS)",
     "new_message": "Új üzenet",
diff --git a/locales/it/common.json b/locales/it/common.json
index 56fc10b42..d0cdd0cda 100644
--- a/locales/it/common.json
+++ b/locales/it/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Richiedi una conferma di lettura",
     "dsn_on": "Notifica di consegna richiesta (clic per disattivare)",
     "dsn_off": "Richiedi una notifica di consegna",
+    "format_plain_text": "Passa a testo semplice",
+    "format_rich_text": "Passa a testo formattato (HTML)",
     "require_tls_on": "Consegna cifrata obbligatoria (clic per disattivare)",
     "require_tls_off": "Richiedi consegna cifrata (TLS)",
     "new_message": "Nuovo messaggio",
diff --git a/locales/ja/common.json b/locales/ja/common.json
index 0e0f8736a..f9c017784 100644
--- a/locales/ja/common.json
+++ b/locales/ja/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "開封確認を要求する",
     "dsn_on": "配信通知を要求中（クリックで解除）",
     "dsn_off": "配信通知を要求する",
+    "format_plain_text": "プレーンテキストに切り替え",
+    "format_rich_text": "リッチテキスト (HTML) に切り替え",
     "require_tls_on": "暗号化配信を必須にしています（クリックで解除）",
     "require_tls_off": "暗号化配信を必須にする（TLS）",
     "new_message": "新規メッセージ",
diff --git a/locales/ko/common.json b/locales/ko/common.json
index 7b61d8cea..115130fed 100644
--- a/locales/ko/common.json
+++ b/locales/ko/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "읽음 확인 요청",
     "dsn_on": "배달 알림 요청됨 (클릭하여 해제)",
     "dsn_off": "배달 알림 요청",
+    "format_plain_text": "일반 텍스트로 전환",
+    "format_rich_text": "서식 있는 텍스트(HTML)로 전환",
     "require_tls_on": "암호화 전송 필수 (클릭하여 해제)",
     "require_tls_off": "암호화 전송 필수 (TLS)",
     "new_message": "새 메시지",
diff --git a/locales/lv/common.json b/locales/lv/common.json
index df9cea352..f192d88b9 100644
--- a/locales/lv/common.json
+++ b/locales/lv/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Pieprasīt lasīšanas apstiprinājumu",
     "dsn_on": "Piegādes paziņojums pieprasīts (noklikšķiniet, lai atspējotu)",
     "dsn_off": "Pieprasīt piegādes paziņojumu",
+    "format_plain_text": "Pārslēgt uz vienkāršu tekstu",
+    "format_rich_text": "Pārslēgt uz formatētu tekstu (HTML)",
     "require_tls_on": "Nepieciešama šifrēta piegāde (noklikšķiniet, lai atspējotu)",
     "require_tls_off": "Pieprasīt šifrētu piegādi (TLS)",
     "new_message": "Jauns ziņojums",
diff --git a/locales/mn/common.json b/locales/mn/common.json
index acd84e4bf..0086c0688 100644
--- a/locales/mn/common.json
+++ b/locales/mn/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Уншсан баримт хүсэх",
     "dsn_on": "Хүргэлтийн мэдэгдэл хүссэн (идэвхгүй болгох бол дарна уу)",
     "dsn_off": "Хүргэлтийн мэдэгдэл хүсэх",
+    "format_plain_text": "Энгийн текст рүү шилжих",
+    "format_rich_text": "Форматтай текст (HTML) рүү шилжих",
     "require_tls_on": "Шифрлэгдсэн хүргэлт шаардлагатай (идэвхгүй болгох бол дарна уу)",
     "require_tls_off": "Шифрлэгдсэн хүргэлт шаардах (TLS)",
     "new_message": "Шинэ мессеж",
diff --git a/locales/nb/common.json b/locales/nb/common.json
index 2488e5897..a6005b906 100644
--- a/locales/nb/common.json
+++ b/locales/nb/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Be om lesebekreftelse",
     "dsn_on": "Leveringsvarsel forespurt (klikk for å slå av)",
     "dsn_off": "Be om leveringsvarsel",
+    "format_plain_text": "Bytt til ren tekst",
+    "format_rich_text": "Bytt til formatert tekst (HTML)",
     "require_tls_on": "Kryptert levering kreves (klikk for å slå av)",
     "require_tls_off": "Krev kryptert levering (TLS)",
     "new_message": "Ny melding",
diff --git a/locales/nl/common.json b/locales/nl/common.json
index 609080211..c3c838bb2 100644
--- a/locales/nl/common.json
+++ b/locales/nl/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Leesbevestiging aanvragen",
     "dsn_on": "Bezorgmelding aangevraagd (klik om uit te schakelen)",
     "dsn_off": "Bezorgmelding aanvragen",
+    "format_plain_text": "Overschakelen naar platte tekst",
+    "format_rich_text": "Overschakelen naar opgemaakte tekst (HTML)",
     "require_tls_on": "Versleutelde bezorging vereist (klik om uit te schakelen)",
     "require_tls_off": "Versleutelde bezorging vereisen (TLS)",
     "new_message": "Nieuw bericht",
diff --git a/locales/pl/common.json b/locales/pl/common.json
index 43008f0b5..3cd722eed 100644
--- a/locales/pl/common.json
+++ b/locales/pl/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Zażądaj potwierdzenia przeczytania",
     "dsn_on": "Zażądano powiadomienia o dostarczeniu (kliknij, aby wyłączyć)",
     "dsn_off": "Zażądaj powiadomienia o dostarczeniu",
+    "format_plain_text": "Przełącz na zwykły tekst",
+    "format_rich_text": "Przełącz na tekst sformatowany (HTML)",
     "require_tls_on": "Wymagane szyfrowane dostarczenie (kliknij, aby wyłączyć)",
     "require_tls_off": "Wymagaj szyfrowanego dostarczenia (TLS)",
     "new_message": "Nowa wiadomość",
diff --git a/locales/pt/common.json b/locales/pt/common.json
index 794b1adf5..e292d189f 100644
--- a/locales/pt/common.json
+++ b/locales/pt/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Solicitar confirmação de leitura",
     "dsn_on": "Notificação de entrega pedida (clique para desativar)",
     "dsn_off": "Pedir notificação de entrega",
+    "format_plain_text": "Mudar para texto simples",
+    "format_rich_text": "Mudar para texto formatado (HTML)",
     "require_tls_on": "Entrega cifrada obrigatória (clique para desativar)",
     "require_tls_off": "Exigir entrega cifrada (TLS)",
     "new_message": "Nova Mensagem",
diff --git a/locales/ro/common.json b/locales/ro/common.json
index 8b16ce5df..6f878c573 100644
--- a/locales/ro/common.json
+++ b/locales/ro/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Solicitați o confirmare de citire",
     "dsn_on": "Notificare de livrare solicitată (clic pentru a dezactiva)",
     "dsn_off": "Solicită o notificare de livrare",
+    "format_plain_text": "Comută la text simplu",
+    "format_rich_text": "Comută la text formatat (HTML)",
     "require_tls_on": "Livrare criptată obligatorie (clic pentru a dezactiva)",
     "require_tls_off": "Impune livrare criptată (TLS)",
     "new_message": "Mesaj nou",
diff --git a/locales/ru/common.json b/locales/ru/common.json
index 08f625683..e8e4fb715 100644
--- a/locales/ru/common.json
+++ b/locales/ru/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Запросить уведомление о прочтении",
     "dsn_on": "Запрошено уведомление о доставке (нажмите, чтобы отключить)",
     "dsn_off": "Запросить уведомление о доставке",
+    "format_plain_text": "Переключить на простой текст",
+    "format_rich_text": "Переключить на форматированный текст (HTML)",
     "require_tls_on": "Требуется зашифрованная доставка (нажмите, чтобы отключить)",
     "require_tls_off": "Требовать зашифрованную доставку (TLS)",
     "new_message": "Новое письмо",
diff --git a/locales/sk/common.json b/locales/sk/common.json
index 9258a8699..89bec8f37 100644
--- a/locales/sk/common.json
+++ b/locales/sk/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Požiadať o potvrdenie o prečítaní",
     "dsn_on": "Oznámenie o doručení vyžiadané (kliknutím vypnete)",
     "dsn_off": "Vyžiadať oznámenie o doručení",
+    "format_plain_text": "Prepnúť na obyčajný text",
+    "format_rich_text": "Prepnúť na formátovaný text (HTML)",
     "require_tls_on": "Šifrované doručenie vyžadované (kliknutím vypnete)",
     "require_tls_off": "Vyžadovať šifrované doručenie (TLS)",
     "new_message": "Nová správa",
diff --git a/locales/tr/common.json b/locales/tr/common.json
index 83b84155d..21442e56c 100644
--- a/locales/tr/common.json
+++ b/locales/tr/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Okundu bilgisi iste",
     "dsn_on": "Teslimat bildirimi istendi (kapatmak için tıklayın)",
     "dsn_off": "Teslimat bildirimi iste",
+    "format_plain_text": "Düz metne geç",
+    "format_rich_text": "Zengin metne (HTML) geç",
     "require_tls_on": "Şifreli teslimat zorunlu (kapatmak için tıklayın)",
     "require_tls_off": "Şifreli teslimat zorunlu kıl (TLS)",
     "new_message": "Yeni İleti",
diff --git a/locales/uk/common.json b/locales/uk/common.json
index 57801765d..ea6a0f82f 100644
--- a/locales/uk/common.json
+++ b/locales/uk/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "Запитати сповіщення про прочитання",
     "dsn_on": "Запитано сповіщення про доставку (натисніть, щоб вимкнути)",
     "dsn_off": "Запитати сповіщення про доставку",
+    "format_plain_text": "Перемкнути на простий текст",
+    "format_rich_text": "Перемкнути на форматований текст (HTML)",
     "require_tls_on": "Потрібна зашифрована доставка (натисніть, щоб вимкнути)",
     "require_tls_off": "Вимагати зашифровану доставку (TLS)",
     "new_message": "Нове повідомлення",
diff --git a/locales/zh-TW/common.json b/locales/zh-TW/common.json
index 7c7b98ade..a81b0da65 100644
--- a/locales/zh-TW/common.json
+++ b/locales/zh-TW/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "請求已讀回執",
     "dsn_on": "已要求遞送通知（點擊停用）",
     "dsn_off": "要求遞送通知",
+    "format_plain_text": "切換為純文字",
+    "format_rich_text": "切換為 HTML 格式文字",
     "require_tls_on": "已要求加密遞送（點擊停用）",
     "require_tls_off": "要求加密遞送 (TLS)",
     "new_message": "新郵件",
diff --git a/locales/zh/common.json b/locales/zh/common.json
index 597ca07c7..49ebc9727 100644
--- a/locales/zh/common.json
+++ b/locales/zh/common.json
@@ -585,6 +585,8 @@
     "read_receipt_off": "请求已读回执",
     "dsn_on": "已请求投递通知（点击禁用）",
     "dsn_off": "请求投递通知",
+    "format_plain_text": "切换为纯文本",
+    "format_rich_text": "切换为富文本 (HTML)",
     "require_tls_on": "已要求加密投递（点击禁用）",
     "require_tls_off": "要求加密投递 (TLS)",
     "new_message": "新邮件",