diff --git a/.env.example b/.env.example
index b358013e1..c6eee95c6 100644
--- a/.env.example
+++ b/.env.example
@@ -314,6 +314,11 @@ LOGIN_COMPANY_NAME=Bulwark Webmail
 # URL for the company website link on the login page.
 LOGIN_WEBSITE_URL=https://bulwarkmail.org
 
+# Placeholder of the email field on the login page, for example your own
+# address format. It replaces the translated example in every language.
+# Unset uses the translation.
+# LOGIN_USERNAME_PLACEHOLDER=user@company.example
+
 # Where users get the source code of this build, linked from Settings >
 # About. Bulwark is AGPL-3.0-only: if you run a modified build, set this to
 # the source of exactly what you deploy (your fork, at the deployed commit).
@@ -375,7 +380,7 @@ LOGIN_WEBSITE_URL=https://bulwarkmail.org
 # Overridable keys: appName, appShortName, appDescription, faviconUrl,
 # pwaIconUrl, pwaThemeColor, pwaBackgroundColor, appLogoLightUrl,
 # appLogoDarkUrl, loginLogoLightUrl, loginLogoDarkUrl, loginCompanyName,
-# loginImprintUrl, loginPrivacyPolicyUrl, loginWebsiteUrl,
+# loginImprintUrl, loginPrivacyPolicyUrl, loginWebsiteUrl, loginUsernamePlaceholder,
 # accessibilityStatementUrl, accessibilityFeedbackUrl, helpUrl, easyReadUrl,
 # signLanguageUrl.
 #
diff --git a/app/(main)/[locale]/login/__tests__/login-page-i18n.test.tsx b/app/(main)/[locale]/login/__tests__/login-page-i18n.test.tsx
index 2695161a8..ec200e05b 100644
--- a/app/(main)/[locale]/login/__tests__/login-page-i18n.test.tsx
+++ b/app/(main)/[locale]/login/__tests__/login-page-i18n.test.tsx
@@ -18,6 +18,8 @@ vi.mock('@/i18n/navigation', () => ({
   Link: ({ children }: { children: React.ReactNode }) => children,
 }));
 
+const configOverrides = vi.hoisted(() => ({ value: {} as Record<string, unknown> }));
+
 vi.mock('@/hooks/use-config', () => ({
   useConfig: () => ({
     appName: 'Webmail',
@@ -30,6 +32,7 @@ vi.mock('@/hooks/use-config', () => ({
     loginShowVersion: true,
     loginShowTotp: true,
     loginShowRememberMe: true,
+    ...configOverrides.value,
   }),
 }));
 
@@ -63,6 +66,22 @@ describe('login page translations', () => {
     act(() => { fireEvent.keyDown(document, { key: 'Escape' }); });
     expect(trigger).toHaveAttribute('aria-expanded', 'false');
   }, 30_000);
+
+  it('uses the translated email placeholder unless one is configured (#1423)', async () => {
+    const { unmount } = render(<LoginPage />);
+    expect(await screen.findByLabelText('username_label', {}, { timeout: 10000 }))
+      .toHaveAttribute('placeholder', 'username_placeholder');
+    unmount();
+
+    configOverrides.value = { loginUsernamePlaceholder: 'max.mustermann@acme.example' };
+    try {
+      render(<LoginPage />);
+      expect(await screen.findByLabelText('username_label', {}, { timeout: 10000 }))
+        .toHaveAttribute('placeholder', 'max.mustermann@acme.example');
+    } finally {
+      configOverrides.value = {};
+    }
+  }, 30_000);
 });
 
 describe('login page notices', () => {
diff --git a/app/(main)/[locale]/login/page.tsx b/app/(main)/[locale]/login/page.tsx
index f0a50a57a..e633a0ce4 100644
--- a/app/(main)/[locale]/login/page.tsx
+++ b/app/(main)/[locale]/login/page.tsx
@@ -200,7 +200,7 @@ function LoginPageContent() {
   usePrefetchMailView(!isMobileHandoff);
   const { login, loginWithToken, loginDemo, isLoading, error, clearError, isAuthenticated } = useAuthStore();
   const { theme, setTheme, initializeTheme } = useThemeStore(useShallow((s) => ({ theme: s.theme, setTheme: s.setTheme, initializeTheme: s.initializeTheme })));
-  const { appName, jmapServerUrl: configuredServerUrl, oauthEnabled, oauthOnly, oauthClientId: globalOauthClientId, oauthIssuerUrl: globalOauthIssuerUrl, oauthScopes, rememberMeEnabled, devMode, demoMode, loginLogoLightUrl, loginLogoDarkUrl, loginCompanyName, loginImprintUrl, loginPrivacyPolicyUrl, loginWebsiteUrl, loginLogoMaxHeight, loginLogoMaxWidth, loginShowHeading, loginShowSubtitle, loginShowTotp, loginShowTokenLogin, loginShowRememberMe, loginShowVersion, isLoading: configLoading, error: configError, autoSsoEnabled, embeddedMode: _embeddedMode, allowCustomJmapEndpoint, jmapServers, jmapServerAutoPickByDomain } = useConfig();
+  const { appName, jmapServerUrl: configuredServerUrl, oauthEnabled, oauthOnly, oauthClientId: globalOauthClientId, oauthIssuerUrl: globalOauthIssuerUrl, oauthScopes, rememberMeEnabled, devMode, demoMode, loginLogoLightUrl, loginLogoDarkUrl, loginCompanyName, loginImprintUrl, loginPrivacyPolicyUrl, loginWebsiteUrl, loginUsernamePlaceholder, loginLogoMaxHeight, loginLogoMaxWidth, loginShowHeading, loginShowSubtitle, loginShowTotp, loginShowTokenLogin, loginShowRememberMe, loginShowVersion, isLoading: configLoading, error: configError, autoSsoEnabled, embeddedMode: _embeddedMode, allowCustomJmapEndpoint, jmapServers, jmapServerAutoPickByDomain } = useConfig();
   const resolvedTheme = useThemeStore((s) => s.resolvedTheme);
   const colorModeLocked = usePolicyStore((s) => s.getColorModePolicy().locked);
 
@@ -1520,7 +1520,7 @@ function LoginPageContent() {
                         onFocus={handleUsernameFocus}
                         onKeyDown={handleKeyDown}
                         className="h-11 px-3.5 bg-muted/40 border-border/60 rounded-xl focus:bg-background focus:border-primary/50 transition-all duration-200"
-                        placeholder={t("username_placeholder")}
+                        placeholder={loginUsernamePlaceholder || t("username_placeholder")}
                         required={!signInWithToken}
                         // Password managers fill and save the pair by this (WCAG 3.3.8).
                         autoComplete="username"
diff --git a/app/(main)/admin/_pages/branding.tsx b/app/(main)/admin/_pages/branding.tsx
index ba368f872..634edb936 100644
--- a/app/(main)/admin/_pages/branding.tsx
+++ b/app/(main)/admin/_pages/branding.tsx
@@ -43,6 +43,7 @@ const TEXT_FIELDS = [
   { key: 'loginImprintUrl', label: 'Imprint URL' },
   { key: 'loginPrivacyPolicyUrl', label: 'Privacy policy URL' },
   { key: 'loginWebsiteUrl', label: 'Company website URL' },
+  { key: 'loginUsernamePlaceholder', label: 'Login email placeholder', placeholder: 'user@company.example' },
 ] as const;
 
 // Accessibility and help links (OP-01): the app shows them on the login
@@ -565,7 +566,7 @@ export function BrandingPage() {
         </SettingsSection>
 
         <SettingsSection id="company" title="Company information">
-          {TEXT_FIELDS.map(field => textRow(field, field.key.includes('Url') ? 'https://...' : 'Enter value'))}
+          {TEXT_FIELDS.map(field => textRow(field, 'placeholder' in field ? field.placeholder : field.key.includes('Url') ? 'https://...' : 'Enter value'))}
         </SettingsSection>
 
         <SettingsSection
diff --git a/app/api/config/route.ts b/app/api/config/route.ts
index acd429bd3..064d58295 100644
--- a/app/api/config/route.ts
+++ b/app/api/config/route.ts
@@ -80,6 +80,7 @@ export async function GET(request: NextRequest) {
       loginImprintUrl: branded<string>('loginImprintUrl', ''),
       loginPrivacyPolicyUrl: branded<string>('loginPrivacyPolicyUrl', ''),
       loginWebsiteUrl: branded<string>('loginWebsiteUrl', ''),
+      loginUsernamePlaceholder: branded<string>('loginUsernamePlaceholder', ''),
       loginLogoMaxHeight: configManager.get<string>('loginLogoMaxHeight', ''),
       loginLogoMaxWidth: configManager.get<string>('loginLogoMaxWidth', ''),
       loginShowHeading: configManager.get<boolean>('loginShowHeading', true),
diff --git a/hooks/use-config.ts b/hooks/use-config.ts
index f41a4a50d..c6fe4908c 100644
--- a/hooks/use-config.ts
+++ b/hooks/use-config.ts
@@ -31,6 +31,7 @@ export interface ConfigData {
   loginImprintUrl: string;
   loginPrivacyPolicyUrl: string;
   loginWebsiteUrl: string;
+  loginUsernamePlaceholder: string;
   loginLogoMaxHeight: string;
   loginLogoMaxWidth: string;
   loginShowHeading: boolean;
@@ -182,6 +183,7 @@ export function useConfig(): AppConfig {
     loginImprintUrl: configCache?.loginImprintUrl || '',
     loginPrivacyPolicyUrl: configCache?.loginPrivacyPolicyUrl || '',
     loginWebsiteUrl: configCache?.loginWebsiteUrl || '',
+    loginUsernamePlaceholder: configCache?.loginUsernamePlaceholder || '',
     loginLogoMaxHeight: configCache?.loginLogoMaxHeight || '',
     loginLogoMaxWidth: configCache?.loginLogoMaxWidth || '',
     loginShowHeading: configCache?.loginShowHeading ?? true,
@@ -233,6 +235,7 @@ export function useConfig(): AppConfig {
         loginImprintUrl: configCache.loginImprintUrl,
         loginPrivacyPolicyUrl: configCache.loginPrivacyPolicyUrl,
         loginWebsiteUrl: configCache.loginWebsiteUrl,
+        loginUsernamePlaceholder: configCache.loginUsernamePlaceholder,
         loginLogoMaxHeight: configCache.loginLogoMaxHeight,
         loginLogoMaxWidth: configCache.loginLogoMaxWidth,
         loginShowHeading: configCache.loginShowHeading,
@@ -285,6 +288,7 @@ export function useConfig(): AppConfig {
           loginImprintUrl: data.loginImprintUrl,
           loginPrivacyPolicyUrl: data.loginPrivacyPolicyUrl,
           loginWebsiteUrl: data.loginWebsiteUrl,
+          loginUsernamePlaceholder: data.loginUsernamePlaceholder,
           loginLogoMaxHeight: data.loginLogoMaxHeight,
           loginLogoMaxWidth: data.loginLogoMaxWidth,
           loginShowHeading: data.loginShowHeading,
diff --git a/lib/__tests__/config-route.test.ts b/lib/__tests__/config-route.test.ts
index 0fa859971..5b88569bf 100644
--- a/lib/__tests__/config-route.test.ts
+++ b/lib/__tests__/config-route.test.ts
@@ -36,6 +36,7 @@ const MANAGED_ENV = [
   'LOGIN_IMPRINT_URL', 'LOGIN_PRIVACY_POLICY_URL', 'LOGIN_WEBSITE_URL', 'DOMAIN_BRANDING',
   'JMAP_SERVERS', 'JMAP_SERVER_AUTO_PICK_BY_DOMAIN', 'SOURCE_CODE_URL', 'LOGIN_SHOW_REMEMBER_ME',
   'ACCESSIBILITY_STATEMENT_URL', 'ACCESSIBILITY_FEEDBACK_URL', 'HELP_URL', 'EASY_READ_URL', 'SIGN_LANGUAGE_URL',
+  'LOGIN_USERNAME_PLACEHOLDER',
 ] as const;
 
 describe('config API route', () => {
@@ -163,6 +164,13 @@ describe('config API route', () => {
     expect(config.loginWebsiteUrl).toBe('https://acme.com');
   });
 
+  it('publishes the login email placeholder, empty when unset (#1423)', async () => {
+    expect((await getConfig()).loginUsernamePlaceholder).toBe('');
+
+    vi.stubEnv('LOGIN_USERNAME_PLACEHOLDER', 'max.mustermann@acme.example');
+    expect((await getConfig()).loginUsernamePlaceholder).toBe('max.mustermann@acme.example');
+  });
+
   it('publishes the source code URL for the About card (#1161)', async () => {
     vi.stubEnv('SOURCE_CODE_URL', 'https://git.example.com/acme/webmail/tree/v1.2.3');
 
@@ -310,6 +318,16 @@ describe('config API route', () => {
       expect(config.helpUrl).toBe('https://default.example/help');
     });
 
+    it('overrides the login email placeholder per domain (#1423)', async () => {
+      vi.stubEnv('LOGIN_USERNAME_PLACEHOLDER', 'name@default.example');
+      vi.stubEnv('DOMAIN_BRANDING', JSON.stringify([
+        { host: 'mail1.example.com', loginUsernamePlaceholder: 'name@one.example' },
+      ]));
+
+      expect((await getConfig({ host: 'mail1.example.com' })).loginUsernamePlaceholder).toBe('name@one.example');
+      expect((await getConfig({ host: 'other.example.com' })).loginUsernamePlaceholder).toBe('name@default.example');
+    });
+
     it('falls through to the global value when the host has no entry', async () => {
       vi.stubEnv('LOGIN_COMPANY_NAME', 'Default Co');
       vi.stubEnv('DOMAIN_BRANDING', JSON.stringify([
diff --git a/lib/__tests__/fixtures/config.ts b/lib/__tests__/fixtures/config.ts
index 02f2ab39f..c764c4e05 100644
--- a/lib/__tests__/fixtures/config.ts
+++ b/lib/__tests__/fixtures/config.ts
@@ -24,6 +24,7 @@ export function createConfig(overrides: Partial<ConfigData> = {}): ConfigData {
     loginImprintUrl: '',
     loginPrivacyPolicyUrl: '',
     loginWebsiteUrl: '',
+    loginUsernamePlaceholder: '',
     loginLogoMaxHeight: '',
     loginLogoMaxWidth: '',
     loginShowHeading: true,
diff --git a/lib/admin/domain-branding.ts b/lib/admin/domain-branding.ts
index 2f84c4fd0..9e878d31f 100644
--- a/lib/admin/domain-branding.ts
+++ b/lib/admin/domain-branding.ts
@@ -27,6 +27,7 @@ export const BRANDING_OVERRIDE_KEYS = [
   'loginImprintUrl',
   'loginPrivacyPolicyUrl',
   'loginWebsiteUrl',
+  'loginUsernamePlaceholder',
   'accessibilityStatementUrl',
   'accessibilityFeedbackUrl',
   'helpUrl',
@@ -61,6 +62,7 @@ export interface DomainBrandingEntry {
   loginImprintUrl?: string;
   loginPrivacyPolicyUrl?: string;
   loginWebsiteUrl?: string;
+  loginUsernamePlaceholder?: string;
   accessibilityStatementUrl?: string;
   accessibilityFeedbackUrl?: string;
   helpUrl?: string;
diff --git a/lib/admin/types.ts b/lib/admin/types.ts
index 6d4110539..09246ba32 100644
--- a/lib/admin/types.ts
+++ b/lib/admin/types.ts
@@ -263,6 +263,9 @@ export const CONFIG_ENV_MAP: Record<string, { envVar: string; fileEnvVar?: strin
   loginImprintUrl: { envVar: 'LOGIN_IMPRINT_URL', type: 'url', defaultValue: '' },
   loginPrivacyPolicyUrl: { envVar: 'LOGIN_PRIVACY_POLICY_URL', type: 'url', defaultValue: '' },
   loginWebsiteUrl: { envVar: 'LOGIN_WEBSITE_URL', type: 'url', defaultValue: '' },
+  // Placeholder of the email field on the login page, e.g. the company's own
+  // address format. Empty uses the translation (login.username_placeholder).
+  loginUsernamePlaceholder: { envVar: 'LOGIN_USERNAME_PLACEHOLDER', type: 'string', defaultValue: '' },
   // Where users get the source of the build they are running (AGPL-3.0 §13).
   // Operators of a modified build point it at their fork; the About card then
   // links there instead of the upstream repository (#1161). Empty = upstream.
diff --git a/lib/config-validation.ts b/lib/config-validation.ts
index 2d145421e..a9d1a7b4a 100644
--- a/lib/config-validation.ts
+++ b/lib/config-validation.ts
@@ -48,6 +48,7 @@ const configValidators = {
   loginImprintUrl: isString,
   loginPrivacyPolicyUrl: isString,
   loginWebsiteUrl: isString,
+  loginUsernamePlaceholder: isString,
   loginLogoMaxHeight: isString,
   loginLogoMaxWidth: isString,
   loginShowHeading: isBoolean,
diff --git a/lib/lite-config.ts b/lib/lite-config.ts
index 8054d87c4..18047896b 100644
--- a/lib/lite-config.ts
+++ b/lib/lite-config.ts
@@ -81,6 +81,7 @@ export function applyLiteConfig(raw: unknown, defaults?: { jmapServerUrl?: strin
     loginImprintUrl: str(input.loginImprintUrl, ''),
     loginPrivacyPolicyUrl: str(input.loginPrivacyPolicyUrl, ''),
     loginWebsiteUrl: str(input.loginWebsiteUrl, ''),
+    loginUsernamePlaceholder: str(input.loginUsernamePlaceholder, ''),
     loginLogoMaxHeight: str(input.loginLogoMaxHeight, ''),
     loginLogoMaxWidth: str(input.loginLogoMaxWidth, ''),
     loginShowHeading: bool(input.loginShowHeading, true),