How to Add an Email Signature in Apple Mail (macOS)

Install a custom HTML email signature in Apple Mail on your Mac. This guide covers the file-based method, how to lock the signature so Mail keeps your formatting, and troubleshooting. Free signature generator included.

Create your free Apple Mail signature →

Step-by-step for Apple Mail on macOS

1. Create your signature in TooStamply and copy the HTML.
2. In Mail, open Settings → Signatures and create a new placeholder signature.
3. Quit Mail so it saves the signature file to disk.
4. Open the signature .mailsignature file in the AllSignatures folder and replace its body with your HTML.
5. Lock the file (Get Info → Locked) so Mail does not overwrite your formatting.
6. Reopen Mail and select the signature for your account.