Florian Ziegler Florian Ziegler
2013-02-26 22:15

Create an updatable signature for Mail.app

Disclaimer: Wether you should even use (HTML) formatting in e-mails is not subject of this post. There is much discussion to be had, on how e-mail was intended to be used in the first place and what has become of it.

Fact is: people like to style their signatures. So here it goes…

  1. Create your signature in HTML. Wrap it all in a <div>. Use only inline CSS to style your elements (some of it will be overwritten by some e-mail clients regardless). It could look something like this:

    e-mail signature

    You should always use absolute references when embedding images.1

    Loading image(s)2 from your web server also gives you the chance to change them, whenever you like. Whenever somebody opens an e-mail containing your signature it will grab the image from your web server. Once you change it, the new image will be loaded. Your signature will change even in older e-mails in people’s e-mail archives. Hence: updatable signature.

    Bonus feature: Additionally you can link the image to a special url, that you redirect to any page on your website. Change the redirection at will…

  2. Create a new signature in Apple Mail. Go to “Preferences”, chose the “signature”-tab, then hit the “+” on the bottom. You can write whatever you want. It doesn’t matter, because all of it will be replaced in a second anyway.
  3. Close Mail.app.
  4. Find the signature you just created: It should be in the “~/Library/Mail/V2/MailData/Signatures/” folder. Order the files by date to find the signature you just created. It sould be a .mailsignature file. Open it in your favorite text editor.
  5. Replace everything between the <body>-tags with the html you created in step 1 and save.
  6. You then need to lock the file, because Mail.app will try to overwrite the changes you just made. Right-click on it and chose “Get info”. Then hit the checkbox next to “Locked”.
  7. Reopen Mail.app and use your new signature!

Credit where it is due: I first learned about how to make a custom css signature in Mail.app on allforces.com.

  1. Do not – and I repeat: DO NOT – use attachments! There is nothing more annoying than people sending the same image attachments with every single e-mail! ↩
  2. I made the image double the size that I needed and shrunk it back down in html. That way I have a crisp image on devices with a retina display, like the iPhone. ↩