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 <key>SupportedPluginCompatibilityUUIDs</key>.

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 <string> 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.

10. November 2010 by Matt Chandler
Categories: Mail.app, NMU news, Tips & Tricks | Tags: , , , | 79 comments

Comments (79)

  1. Pingback: MacTalk Podcast #148 – Print it On a Cheeseburger | MacTalk Australia

  2. Pingback: GPGMail と Letterbox、Mac OS 10.6.5 « VK test

  3. THANK YOU!!!! worked like a charm! Can someone talk some sense into Steve Jobs? the guy is a freaking control freak!

  4. many thanks!

    kind regards. m.

  5. Yay! it worked! thanks!

  6. Can’t be without my letterbox – your fix worked perfectly.

  7. thanks a lot. worked like a charm!

  8. lovely, works like a charm

  9. Thanks a lot, Letterbox and Growl works perfectly!

    Couldn’t ask for an easier fix.

  10. Pingback: Mailを3コラムにするプラグイン “Letterbox” をMac OS X 10.6.5で使用可能にする方法 [Mac] | No Second Life

  11. worked like a charm!

  12. It worked!

    I think people are getting confused when they see “Bundles (Disabled 3)”, “Bundles (Disabled 4)”, “Bundles (Disabled 5)” etc. I had the same problem. What I did was:

    1. I went to the most recent “Bundles (Disabled 5)”
    2. Followed the directions above.
    3. Renamed ORIGINAL “Bundles” folder to “Bundles (Disabled 6) and DELETED “(Disabled 5)” from “Bundles (Disabled 5)” – making it the NEW ORIGINAL
    4. Opened MacMail and VOILA! WORKS!!

  13. Thanks! Worked an absolute treat – bravo!! LOVE this plugin!


  14. It works good! Thanks!!

  15. THANKS a lot my friend !
    cheers from Cologne – chris.

  16. Great! Thank you!

  17. Thanks for the fix! Even on a 27″ display, the horizontal layout in Mail feels cramped. Letterbox is a must-have!

  18. Thanks for the quick fix on one of the most useful features in OS X. I also applied the fix to mail.appetizer – it all works great!

  19. Cool. Worked perfectly and took about 2 minutes (including finding and installing TextWrangler).


  20. Brilliant thank you. I just deleted all the ‘disabled folders and edited the original plist file in textedit (no need for additional programmes).

    Why on earth do Apple not sort this!?

  21. i deleted all the “disabled folders,” re-installed the plugin, then edited as above.

    it worked :)

  22. The plugin has been updated.

  23. Thanks! Worked perfectly. And your willingness to add that we could use this on other disabled bundles was very kind. Now my MTags is as happy as my LBox!

  24. Thank you. It works perfectly!!!
    So glad that my mail looks nice again. I cannot live without Letterbox.
    Thank you!!!

  25. Thanks! Worked perfectly. And your willingness to add that we could use this on other disabled bundles was very kind. Now my MTags is as happy as my LBox!

  26. Getting the message that the Letterbox app isn’t compatible w/the Mail version 4.5. Can you help?
    I’ll be glad to send you my file for editing.
    With thanks,

  27. This was a great help – many thanks

  28. Hi All,

    Just ant to know is the fix can fix the Macbook air connect to Exchange 2003 issue?

    Many thanks

  29. Typo: Just want to know is the fix can fix the Macbook air connect to Exchange 2003 issue?