diff --git a/components/email/__tests__/recipient-mention.test.tsx b/components/email/__tests__/recipient-mention.test.tsx
index 851e3a42b..98cacbc02 100644
--- a/components/email/__tests__/recipient-mention.test.tsx
+++ b/components/email/__tests__/recipient-mention.test.tsx
@@ -189,6 +189,21 @@ describe('RecipientMention insertion', () => {
     editor.destroy();
   });
 
+  it('never lets a click on a chip follow its mailto link', () => {
+    // Firefox follows a link in a non-editable island of the editor.
+    const { editor } = setup('<p>Hi <a href="mailto:eva.weber@dornig.de">@Eva</a> and <a href="mailto:info@dornig.de">us</a></p>');
+    document.body.appendChild(editor.view.dom);
+    const chip = editor.view.dom.querySelector('a.mention')!;
+    const click = new MouseEvent('click', { bubbles: true, cancelable: true });
+    chip.dispatchEvent(click);
+    expect(click.defaultPrevented).toBe(true);
+    const middle = new MouseEvent('auxclick', { bubbles: true, cancelable: true, button: 1 });
+    chip.dispatchEvent(middle);
+    expect(middle.defaultPrevented).toBe(true);
+    editor.view.dom.remove();
+    editor.destroy();
+  });
+
   it('turns a sent mention back into a chip, and leaves other mailto links alone', () => {
     const { editor } = setup(
       '<p>Hi <a href="mailto:eva.weber@dornig.de">@Eva</a> and <a href="mailto:info@dornig.de">write us</a></p>',
diff --git a/components/email/mention-chip.tsx b/components/email/mention-chip.tsx
index ee89437ba..a3ef586cc 100644
--- a/components/email/mention-chip.tsx
+++ b/components/email/mention-chip.tsx
@@ -77,6 +77,20 @@ export const MentionChip = Node.create({
           },
         },
         props: {
+          // The chip is a mailto: link that isn't editable, and Firefox
+          // follows such links even inside the editor - asking which app
+          // should write the mail. A click only selects it (and opens the
+          // card); ProseMirror's selection doesn't rely on the default.
+          handleDOMEvents: {
+            click: (_view, event) => {
+              if ((event.target as Element | null)?.closest?.("a.mention")) event.preventDefault();
+              return false;
+            },
+            auxclick: (_view, event) => {
+              if ((event.target as Element | null)?.closest?.("a.mention")) event.preventDefault();
+              return false;
+            },
+          },
           decorations(state) {
             const recipients = mentionRecipientsKey.getState(state);
             if (!recipients) return null;