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Custom iPhone/iPad Signature CSS

  1. Your iPhone must be jailbroken.
  2. Basic understanding of HTML/CSS and an editor that can edit .plist files, such as PList Edit Pro.
  3. Ability to SSH into your jailbroken iPhone.


Log into your iPhone over AFP, browse to the following location:


Copy the file com.apple.mobilemail.plist to your Mac. Go ahead and duplicate this file, appending “backup” to the end of the filename so you have a clean copy in case something goes wrong.


Open your email signature that we created (see EMAIL SIG.CSS below) in your HTML editor and copy the contents to the clipboard.


Use PlistEdit Pro to open the file you copied earlier in Step One. Towards the bottom of the list, you will see an entry called “SignatureKey.” The value for this string will match your current iPhone signature.

Double-click this value to highlight the contents and delete what’s there. Now paste the HTML code for your email signature that we copied in Step Two. Save this file back to your desktop.


Browse back to the Preferences folder on your iPhone. Copy our new edited plist file and replace the original on your iPhone.


All done! Create a new email and you should see your HTML email signature at the bottom.


Sample Signature:

Your Name Blogger, Designer, Thinker & Nerd
web: yourwebsite.com email: yourname@yourwebsite.com

The Code:

Chris Ryan Blogger, Designer, Thinker & Nerd web: yourwebsite.com email: yourname@yourwebsite.com

You can also add an image to the signature but be sure to convert it to Base64.

2 Responses to “Custom iPhone/iPad Signature CSS”

  1. adam says:

    is it possible to just copy/paste some html into the sig field directly in the settings instead of having to go through the iphones file system and mess with plist files?

  2. Christopher Aceto says:

    Nope. When you try to save the sig the iPhone removes all html/css formatting. It has to be done in the .plist file. If the html code was possible then the you wouldn’t need to jailbreak.

    As much as I love Apple, some of the restrictions are ridiculous.

Leave a Reply to adam

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