10.6.5 Snow Leopard Update Breaks Letterbox Mail.app Plugin – Quick Fix

For you Letterbox – Mail.app plugin lovers out there here is a quick fix to get you back it working in 10.6.5 Snow Leopard. First off you will need the new “SupportedPluginCompatibilityUUIDs”.

  1. 857A142A-AB81-4D99-BECC-D1B55A86D94E
  2. BDD81F4D-6881-4A8D-94A7-E67410089EEB

Then you will need a program to edit info.plist files. If you have developer tools installed you will use Property List Editor if not you will need a program that will edit an .xml file like my favorite Texwrangler.


Next you have to find and edit the info.plist for letterbox. Yours may be a little bit different but by default the file we need  is in You User Folder -> Library -> Mail-> Bundles. If you have opened mail and got the disabled warning message your folder will have “(Disabled)” added to it. For now Leave this alone. Open the folder and you will see a list of the mail plugins you have .

Right click on the Letterbox.mailbundle and select “Show Package Contents” a new Finder window will open and you will see a contents folder, open this and you will see the info.plist file we need to edit. Open it in Textwrangler.app and scrool to the bottom of the file. There you will see the area we need to edit.

Look for (or use the find command) the line SupportedPluginCompatibilityUUIDs.

Once you find this you need to add the 2 strings from above to it. or just copy the next 2 lines and paste it in the file just under the other tags as you see in my screen grab from above, make sure it is before the tag.


Now we need to deal with the “(Disabled)” part of the folder. This is easy just go to the finder and open back to the Mail folder from above and edit the folder name and delete the “(Disabled)” part. If you have other mail plugins you can edit the info.plist file the same way,If you choose not to edit them they will disable again on the next launch of Mail.app. If you have this all done then when you open mail you will be back in business with mail.app and the letterbox plugin.

**** UPDATE***** (11/12/2010 @ 11:07 am est)
I have had 3 people contact me with issues after they edit the info.plist file. I have asked them all to send me a copy of the info.plist file on their machine and all have had either old versions or a very different items in the file. I have asked all of them to re-download the plugin from the original source. (Letterbox Plugin @ Harnly.net)Then prior to opening Mail.app do the edit as above. So Far that has worked for anyone who has had an issue.


  1. Glen

    I can’t tell you how impressed I was with your clear instructions. Letterbox and Rocketbox for Mail seem to become disabled with each update to Mac OS X. But, this instantly fixed both, rather than me having to wait days or weeks for the developers of these two plugins to create new versions. Thanks so much!

  2. Camán

    Great. It works fine now.
    As said before: clear instructions.
    Thanks a million. 🙂

  3. Jimbo

    Wonderful. Thanks for the quick fix. Now if only Apple would listen to its customers and provide this functionality without the need for a plugin.


  4. rivertemple

    It works beautifully. Thank you!

  5. Renatus

    Thank you thank you thank you.
    PS: TextEdit.app works fine as the editor.

  6. Virgil

    Wow, even I managed this with no issues or mistakes. By far the clearest instructions I’ve seen on the web.

    Many thanks!

  7. Andreas

    Brilliant – thanks, it worked as described.

  8. Max Bazarov

    Big thanks!

  9. lpezda

    Works like a charm! Thank You.

  10. Jonas W.

    does not work for me :s help me out ! changed the XML,saved it.. now when i open up mail it says again “disabled plugins : Growl & Letterbox” …

  11. Matt

    @Joans not sure where you problem lies but if you can use the contact form to send me a copy for the info.plist that is in you Bundles folder then I may be able to look at it and help you out.

    Just a suggestion start over and only move the Letterbox plugin in the the Bundles folder. Leave growl out or go into its settings as well and edit the growl info.plist file with the same thing. then try it again. also I would just make sure that mail is closed when you do the edits.

  12. Matt

    @ Everyone else thanks for the comments and glad it is working for you!

  13. Matt

    Yet another suggestion if you run into a problems.

    -Close mail
    -Download a clean copy of letterbox and install it.
    -Navigate to the Bundles folder
    -Edite the info.plist file
    -Launch Mail.app

  14. Jonas W.

    just isolated the Letterbox (so i’ve moved Growl) still same freakin’ error.

    i know my way through XML so i’m véry sure i’ve done it correctly (just copy pasted it..)

    can it be something else? i’m afraid that downloading a fresh copy won’t work,cuz my mail is updated now,so guess he won’t accept that older version anymore,no?…

  15. Jason

    Your a star, crystal clear instructions, worked perfectly.

    Million thanks for your time and efforts to help.

    Makes me feel like an expert user 🙂

  16. sylvie

    thanks a lot
    recovered letterbox and Antidote HD by this way
    very easy

  17. Jonas W.

    @Matt : answered your mail,still not working 🙁

  18. Mark

    A thanks from me as well. My heart sank when once again Apple took Letterbox away. I’m neither a hacker or coder but in a few minutes all was right in my Mail world again.

  19. Tim

    Excellent!! You are a genius and so helpful. Thank you so much!!

  20. Matt

    @Joans I am really not sure why you are having an issue. So far you are the only user who has let me know it is not working. If you want to post your info.plist file here or send me an e-mail I am happy to help in anyway I can. I can even try to do a remote support session if you want. Just respond to my e-mail and we will try to set something up.

  21. Antonio

    great post! ty soooo much!

  22. aitistul

    Super! Thank you very much for your quick post.

  23. Jerry

    Thanks, this worked perfectly!

  24. John D Stackpole

    Thank you!

    Hanley’s webpage appears semi-down so who knows when he will come back to life.

  25. Steve Powley

    Thank-you very much – I really love this plugin and not having it makes mail much poorer. This functionality should be available by default in the app with almost everyone using widescreens these days.

    Come on Apple – do us all a favour.

  26. Ignazio

    Thanks a lot, worked perfectly for Herald, Letterbox and Rocketbox

  27. Dave

    Thank You very much!!!! Great instructions.

  28. Pasi

    Works! Thanks!

  29. Michael Crandell

    You rock!

  30. Tim Searle


  31. Peter Treudler

    Thank you so much, works fine, great instructions :-)))

  32. luciano

    Mail not working anymore after modification

  33. muski

    Thank you, thank you, thank you. Mail without Letterbox is just feels wrong!

  34. John McEnroe

    Thanks a whole lot! Really clear and simple instructions

  35. Dan

    Doesn’t work for me. In my console log, I’m getting the following error:

    Letterbox.mailbundle failed to load. The error was:\nError Domain=NSCocoaErrorDomain Code=3585 UserInfo=0x1012879a0 “The bundle “Letterbox” couldn’t be loaded because it doesn’t contain a version for the current architecture.” (dlopen_preflight(/Users/dan/Library/Mail/Bundles/Letterbox.mailbundle/Contents/MacOS/Letterbox): no suitable image found. Did find:\n /Users/dan/Library/Mail/Bundles/Letterbox.mailbundle/Contents/MacOS/Letterbox: no matching architecture in universal wrapper)

  36. Trisha Cupra

    I love you! I’m by no means a new Mac user, but this is the first time Mail has disabled Letterbox with an update (I was using other email apps in the past).

    The thought of using the default view in Mail seemed fate worse than death, so I’m very happy I found your clear instructions so fast.

    Apple has been making widescreen hardware for years, so it beats me why they don’t have this View option in Mail.

    Many, many thanks. So many people I know are switching to Mac (hallelujah) and I’ll be sure to tell them about your site.

  37. Pawel

    Thank you so much!!!!!

  38. Milo

    Thanks for the solution and instructions.
    Can’t without this plugin.
    Thanks a lot for this quick fix.

  39. Jonas W.

    This is an amazing fix ! 🙂 finally got it working,all thanks to the excellent support from Matt !!!

    Thanks A LOT !

  40. Nickolas

    Thanks, very clear instructions for fixing this.

  41. Bernd

    Thanks a lot, you made my day!!! Perfect description, so it was easy to succeed.
    The TextEdit App, that comes with your Mac, works also fine to edit the info.plist file.

    Thanks again an best regards,

  42. D

    YOU ARE AWESOME. Thanks for taking time out of your day to do this… SUPER COMPLICATED to figure out but SO SIMPLE TO FIX with your instructions.

  43. Eric

    Great instructions. For those that tried wide mail as I did yesterday, you will need to trash the wide mail bundle. In the process I lost my Subject column – (something that seems to be a bug with Wide mail when you remove it). In order to restore the subject column, make sure Mail is closed and then launch Terminal and type this;

    defaults delete com.apple.mail TableColumns

    Your subject column will be restored.

  44. Alex

    Thanks for the “fix” It took me a couple of tries because I had 4 “disabled” bundles I needed to move to trash first then move “bundles” to trash so I would only have one copy of “bundles” Now it works like before upgrade.
    Thank You!

  45. sean

    You did an excellent job outlining a fix. Thanks for the help!

  46. Fotis

    Bravo!Excellent.Many Thanks it worked immediately and even corrected my problem of getting no mail!

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