diff --git a/src/components/__tests__/settings-i18n.test.ts b/src/components/__tests__/settings-i18n.test.ts
new file mode 100644
index 00000000..0141881a
--- /dev/null
+++ b/src/components/__tests__/settings-i18n.test.ts
@@ -0,0 +1,22 @@
+// Settings panes whose every user-visible string goes through t(). A literal
+// English label, description or option label sneaking back in stays English
+// in every locale, so this scans the source for the prop shapes the panes use.
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+
+const TRANSLATED_PANES = ['ReadingSettings.tsx'];
+
+// `label="Foo"`, `description='Foo'`, `placeholder="Foo"` and `{ label: 'Foo' }`
+// with a letter in the text (numeric option labels such as '25' are fine).
+const LITERAL_RE = /\b(label|description|title|placeholder)(=|:\s*)(["'`])[^"'`]*[A-Za-z][^"'`]*\3/g;
+
+describe('translated settings panes', () => {
+  for (const file of TRANSLATED_PANES) {
+    it(`${file} has no hard-coded English labels`, () => {
+      const source = readFileSync(join(__dirname, '..', 'settings', file), 'utf8');
+      const literals = [...source.matchAll(LITERAL_RE)].map((m) => m[0]);
+      expect(literals).toEqual([]);
+    });
+  }
+});
diff --git a/src/components/settings/ReadingSettings.tsx b/src/components/settings/ReadingSettings.tsx
index ccc712e0..20b50a87 100644
--- a/src/components/settings/ReadingSettings.tsx
+++ b/src/components/settings/ReadingSettings.tsx
@@ -291,37 +291,37 @@ export function ReadingSettings() {
         />
       </SettingItem>
 
-      <SettingItem label="Plain Text Font" description="Font used for plain-text messages.">
+      <SettingItem label={t('settings.email_behavior.plain_text_font.label', "Plain Text Font")} description={t('settings.email_behavior.plain_text_font.description', "Font used for plain text emails")}>
         <Select
           value={plainTextFont}
           onChange={(v) => update('plainTextFont', v as PlainTextFont)}
           options={[
-            { value: 'sans', label: 'App font' },
-            { value: 'mono', label: 'Monospace' },
+            { value: 'sans', label: t('settings.email_behavior.plain_text_font.sans', "Normal (same as the app)") },
+            { value: 'mono', label: t('settings.email_behavior.plain_text_font.mono', "Monospace") },
           ]}
         />
       </SettingItem>
 
-      <SettingItem label="Message Spacing" description="Gutter around the message body.">
+      <SettingItem label={t('settings.email_behavior.message_spacing.label', "Message Spacing")} description={t('settings.email_behavior.message_spacing.description', "Padding around the message body in the reader")}>
         <Select
           value={messageSpacing}
           onChange={(v) => update('messageSpacing', v as MessageSpacing)}
           options={[
-            { value: 'auto', label: 'Automatic' },
-            { value: 'always', label: 'Always padded' },
-            { value: 'edge', label: 'Edge to edge' },
+            { value: 'auto', label: t('settings.email_behavior.message_spacing.auto', "Auto (recommended)") },
+            { value: 'always', label: t('settings.email_behavior.message_spacing.always', "Always add spacing") },
+            { value: 'edge', label: t('settings.email_behavior.message_spacing.edge', "Edge to edge") },
           ]}
         />
       </SettingItem>
 
-      <SettingItem label="Read Receipts" description="When a sender asks to be notified that you opened a message.">
+      <SettingItem label={t('settings.email_behavior.read_receipt_response.label', "Respond to read-receipt requests")} description={t('settings.email_behavior.read_receipt_response.description', "What to do when an incoming message asks for a read receipt.")}>
         <Select
           value={readReceiptResponse}
           onChange={(v) => update('readReceiptResponse', v as ReadReceiptResponse)}
           options={[
-            { value: 'ask', label: 'Ask me' },
-            { value: 'always', label: 'Always send' },
-            { value: 'never', label: 'Never send' },
+            { value: 'ask', label: t('settings.email_behavior.read_receipt_response.ask', "Ask each time") },
+            { value: 'always', label: t('settings.email_behavior.read_receipt_response.always', "Always send") },
+            { value: 'never', label: t('settings.email_behavior.read_receipt_response.never', "Never send") },
           ]}
         />
       </SettingItem>