Apple Mail Email Signature

Developer Apple
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What is a MAILSIGNATURE file?

A MAILSIGNATURE file contains an email signature (and accompanying metadata) used by Apple Mail. The email signature is formatted using HTML. Apple Mail stores and loads each of a user's email signatures from a separate MAILSIGNATURE file.

More Information

Screenshot of a .mailsignature file in Apple TextEdit
MAILSIGNATURE file open in Apple TextEdit

Apple Mail is an email application bundled with macOS. Like most email apps, Apple Mail allows users to create email signatures for use as default sign-offs and messages. Typically, Apple Mail users create signatures by:

  1. Selecting Mail → Settings... from Mail's menu bar.
  2. Going to the Signatures screen.
  3. Creating one or more signatures.

Apple Mail saves each email signature that a user creates in a MAILSIGNATURE file. By default, Apple Mail stores MAILSIGNATURE files in the following location:

Macintosh HD/​Users/​YourUserName/​Library/​Mail/​V10/​MailData/​Signatures

Each MAILSIGNATURE file's name consists of a 32-character UUID, which Apple Mail uses to identify that signature. In addition to signature text, each MAILSIGNATURE file also includes a header that identifies the signature's text encoding, content type, message ID, and MIME version.

How to open a MAILSIGNATURE file

In most cases, you should not need to open a MAILSIGNATURE file. If you need to edit an Apple Mail email signature, you must do so from within the application (by selecting Mail → Settings... → Signatures). Editing the signature's MAILSIGNATURE file outside Apple Mail will have no effect.

However, if you want to view a MAILSIGNATURE file's contents outside Apple Mail, you can open it with Apple TextEdit, Microsoft Notepad, or any other text editor.

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Programs that open or reference MAILSIGNATURE files

Included with OS
Included with OS
Included with OS

Verified by FileInfo.com

The FileInfo.com team has independently researched the Apple Mail Email Signature file format and Mac, Windows, and Linux apps listed on this page. Our goal is 100% accuracy and we only publish information about file types that we have verified.

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