Apple Mail

Install an HTML email signature

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Apple Mail has no box for HTML code. Paste the signature as it looks, then turn off Always match my default message font. If Mail strips the layout after you quit, use the file method at the end. That still works on current macOS.

  1. Copy the signature as it looks

    Download your HTML signature file from your company signature page.

    • Open the file in Chrome, Edge or Firefox. Leave Safari for this step. It can change the formatting when you copy.
    • Click the signature, select all with Ctrl+A (Windows) or Cmd+A (Mac), then copy with Ctrl+C or Cmd+C.

    Copy the signature as it looks. If you paste the raw code into a normal signature box, the email will show the code instead of the design.

  2. Paste it into Mail

    1. In Mail, go to Mail → Settings (or press Cmd+,), then click Signatures.
    2. Select your email account, click +, and name it Work signature.
    3. Click in the signature box on the right and paste with Cmd+V.
    4. Untick Always match my default message font. If that stays on, Mail replaces your fonts and colours.
    5. Under Choose Signature, set Work signature for that account.

    Images can look blank in the settings preview. Compose a new email to check the real result.

  3. If Mail strips the layout

    Use this only if the paste loses its design after you quit Mail. Create the blank signature first, if you have not already.

  4. Quit Mail

    Fully quit Mail with Cmd+Q. Mail overwrites the signature file if it stays open.

  5. Open the signature file

    1. In Finder, choose Go → Go to Folder (or press Cmd+Shift+G).
    2. Paste ~/Library/Mail/ and press Return.
    3. Open the highest-numbered V folder (for example V10 or V11), then MailData → Signatures.
    4. Sort by Date Modified and open the newest .mailsignature file in TextEdit. Do not edit any .plist files.

  6. Replace the signature

    1. Download your HTML signature file from your company signature page. Open it in TextEdit and copy the whole file.
    2. In the .mailsignature file, leave the header lines at the very top. Select everything from <body> to </body> and paste your signature in its place.
    3. Save and close the file.

  7. Lock the file

    Right-click the .mailsignature file, choose Get Info, and tick Locked. This stops Mail from rewriting your HTML.

  8. Check it

    Reopen Mail and start a new email. If the signature does not appear, choose Work signature from the signature menu in the compose window, or set it as the default under Mail → Settings → Signatures.

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