Add an HTML email signature for Mail in Mountain Lion

This is seemingly one thing that Apple have never made all that simple to do. Not sure why as so many people want a fancy signature nowadays. Anyway, here’s a quick (not really all that quick, i’m afraid) guide on adding a HTML signature to Apple Mail.

1. Create the HTML signature

I won’t go too much into this as this is a post in itself. So, we’ll presume that you’ve created a lovely HTML email signature that you’re now ready to add to Mail.

The important thing here is that your signature will work well on all email clients. For that I would advice going back to the 90’s and using only tables and very basic formatting in your HTML and remember all CSS should be inline and not in a separate stylesheet.

Finally, if using images then host these on your server and link to them with absolute paths to the image. I test it’s looking good in a fantastic online service provided by Email on Acid.

NOTE: I’ve noticed that Mountain Lion has a tendency to incorrectly display the last bit of code in the HTML so it’s worth adding an extra table cell or table row to the end of your email signature so then it won’t matter if this fails to display.

2. Create a temporary signature in Mail

Open up Mail and go to Mail > Preferences… and click on the Signatures tab. Click the + icon to create a email signature. Name this signature but don’t worry about adding any content to it as we’ll be overwriting this with your new one. Now quit Mail.

3. Make the “Library” folder visible in Mountain Lion

From the Finder go to Applications/Utilities/Terminal and type copy-paste the following and hit return

chflags nohidden ~/Library/

This just makes the necessary Library folder visible on your Mac

4. Copy your HTML email signature

I use Chrome but I’ll stick with the supplied Safari browser for this… Open up the HTML file you created in Step 1, in Safari. Now, go to Safari > Preferences and click on the Advanced tab. Make sure the “Show develop menu in menu bar” is checked and then close this window.

From the menu bar go to Develop > Show Page Source and copy all code between and including the start <body> tag and end </body> tag.

5. Pasting the Source Code

Go back to your Finder and navigate to ~/Library/Mail/V2/MailData/Signatures and locate the newest .mailsignature file (it’s best to look at this folder in List view and then ordering by the Date column.

Right click or Control-Click on the file and choose Open With… Other and open with TextEdit, located in your Applications folder.

Paste the content you copied in Step 4 into place, overwriting everything between and including the start <body> tag and end </body> tag.

Click File > Save

6. Lock the .mailsignature file

This is a vital step. If you don’t do this then Apple will just ignore what you’ve just pasted into that file and revert back to the temporary content we created in Step 2.

Go back to the .mailsignature file in the Finder and select File > Get Info from the menu bar and check the “Locked” checkbox. Close that window.

7. Your new signature

Open Apple Mail and go to Mail > Preferences… and click the Signatures tab. Locate your new signature and now drag and drop that signature onto the account you would like to use it with, in the left column. Don’t worry if you’ve used images in your signature and they are currently showing as broken links. I found that sometimes they showed, sometime they didn’t. The important thing is they show when you add it to an email.

Click on your email account in the Accounts column and select your signature from the “Choose Signature” dropdown. If you want your signature to appear above the quoted text, rather than at the very bottom of emails you reply to then check the “Place your signature above quoted text” checkbox.


As you can see this is not the most straight-forward of procedures but once you have your HTML email signature in Mail then you will never need to do this again… Hopefully!

There may be Apps or scripts that make this process far simpler and I’d be interested to know of any so please do leave a comment below.