Subject Guard for Gmail

About

Ever sent an email and realized — too late — that the subject line was blank? Subject Guard for Gmail makes that impossible.

When you try to send a message with an empty subject, it quietly stops the send. The subject field shakes and turns red, and a small hint appears and fades on its own — no alert to dismiss, no dialog to click through. Add a subject and sending works as normal.

WHAT IT CATCHES
• Clicking the Send button
• The Ctrl+Enter / ⌘+Enter shortcut
• Pressing Enter or Space on a focused Send button

STAYS OUT OF YOUR WAY
• No settings to configure — install it and it works.
• No pop-ups or alerts to close.
• No override button — to send a blank subject, just remove the extension.
• Inline replies keep working normally.

PRIVACY
No data collected, stored, or sent. It runs entirely in your browser on mail.google.com and only checks whether the subject is empty. Your emails never leave your computer.

Free and open source.