Previously, I discussed how to create custom CSS email signatures for Mail in Mac OS X. This week, we’re going to look at what it takes to replicate the same signature on your iPhone. What You Will Need Your Mac Your iPhone (it needs to be […]

iPhone Mail IconPreviously, I discussed how to create custom CSS email signatures for Mail in Mac OS X. This week, we’re going to look at what it takes to replicate the same signature on your iPhone.

What You Will Need

  • Your Mac
  • Your iPhone (it needs to be jailbroken)
  • PlistEdit Pro (or another application capable of editing plists)
  • Coda (or another application for editing HTML)

Before We Begin

To use a custom CSS signature, we will be modifying a preference file on your iPhone. Simply using copy and paste within the new 3.0 OS will not maintain the HTML and formatting of our signature. Your iPhone should already be jailbroken and capable of mounting as an Apple File Protocol (AFP) share on your Mac. For instructions on this process, see here.

Step One

Once you have logged 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.

Step Two

Open your email signature that we created (see the original post here) in your HTML editor and copy the contents to the clipboard.

Step Three

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.

Step Four

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

iPhone HTML EmailStep Five

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


Unfortunately, due to limitations in the iPhone 3.0 OS, Mail on the iPhone only supports one signature. There are third-party applications available on the App Store that address this issue, but I have not tested them with HTML email signatures. Hopefully in a future OS update, Apple will allow users to have unique signatures for multiple mail accounts.

This process and file location has remained the same since iPhone OS 1.1.4 and will likely remain the same, meaning as new OS updates come out, they should not break this functionality (unless Apple adds support for multiple signatures at some point). However, if an update does break your signature, the process outlined above should still work to put it back.

  1. Howie Isaacks Friday, August 21, 2009

    I was all excited about the prospect of being able to do this until I found out that I have to jailbreak my iPhone. FAIL!

    1. failing to realize all the advantages of jailbreaking: FAIL!!!! on you sir

      please, continue being Apple’s slave, we don’t mind

  2. I used PropertyList Editor on my PC and it required changing all the carat symbols in the HTML to ‘<‘ and ‘&gt’ character entities. Otherwise, it worked fine!


    1. The ‘less than’ carat mark was encoded but you get the idea. :)

  3. There’s also a pretty sweet work around to get HTML signatures in mail.app. Here’s a link to the tutorial: http://su.pr/7kvEvG

    That being said, HTML in signatures should be kept to a minimum.

    1. Apex, that’s what Ryan’s last article was all about, and referenced in the very first sentence in this article! :-)


  4. ummm maybe i’m dumb but i can’t get it to work. below is my plist and i think my problem is i’m pasting the new signature into the wrong area:

    bplist00Ú  _LastAccountViewed_ShowToCCIndicators_PlaySentMailSound_ShowMessageHeaderDetails_FontSizeSetting_PlayNewMailSound^LinesOfPreviewSignatureKey_UISuspendedSettings_DCFLastDirectoryNumber_$D39121C3-EB8F-400F-89B2-5676B1DCE565 R13 Q0_Sent wirelesslyÑ_UISuspendedDefaultPNGKeyWDefaultd1FZu‡š©¶Ìå  ’*EMO

    Also, is this plist supposed to be this short? thanks for any help/advice

  5. I have developed one email appending application for online marketers. Now i want to make that application iPhone friendly. Can anyone help me in this case. Which programing language i need to use.

  6. Doesn’t work for me. The iPhones doesn’t show any changes if I’m editing the com.apple.mobilemail.plist-file. Any ideas?

  7. Awesome. Now when would Apple put this in it’s own Mail.app. Workarounds are all nice and all, but then they’re just workarounds .. not the real deal.

  8. [...] den ‘reinen’ Text nicht umzu. Dachte ich, bis ich kürzlich auf dieses Tutorial ‘How-To: Create Custom CSS Email Signatures on the iPhone‘ stieß. Individuelle CSS-Signaturen sollen mit einem Jailbreak-Phone schon länger ewig [...]

  9. For another way, you can try our free iPhone app – search for “Email Signature Lite” in the App Store.

  10. Just awesome! I’m doing this to all my staffs phones :)


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