How To Fix Letterbox Mail plugin for Mac OS X 10.6.5

How To Fix Letterbox Mail plugin for Mac OS X 10.6.5

Letterbox is a popular plugin for that gives you a wide screen three-pane view in Mail, unfortunately the Mac OS X 10.6.5 update broke this plugin. If you don’t mind getting your hands a bit dirty in the Finder, you can fix the plugin to work in 10.6.5 by editing a file. We’ll walk you through it:

Fixing the Letterbox plugin for Mac OS X 10.6.5
1- From the Finder, hit Command+Shift+G and enter ~/Library/Mail/ then hit Go.
2- Open Bundles (Disabled) rather than Bundles .
note: if you have already opened Mail, the plugin is disabled, if you haven’t opened Mail yet, it will be in Bundles

3- Right-click on Letterbox.mailbundle and selectShow Package Contents
4- Now open the “Contents” folder inside the Letterbox.mailbundle contents
5- Using a text editor, open Info.plist (you can use TextEdit, don’t use Word)
6- Scroll to the bottom of the Info.plist file and look for “SupportedPluginCompatibilityUUIDs” which is surrounded by key tags, below that will be a bunch of hex strings surrounded by string tags
7- Add the following two strings to the bottom of the list (inside the array tags):


The newly inserted strings should look as follows:

8- Save these changes to the Info.plist file
9- Go back to the Mac OS X desktop and hit Command+Shift+G again, then enter ~/Library/Mail/
10- You’ll see these two folders again: Bundles and Bundles (Disabled), what you need to do is move the Letterbox.mailbundle plugin from the (Disabled) folder to the Bundles folder. Do this just by dragging the file from one folder window to the other.
11- Relaunch

Now when you open the Mail app again, your Letterbox plugin will be restored and everything should be working in full widescreen three paneled glory again.

Via osxdaily

  • Pete

    This doesn't work for me.

    I still get:

    "Incompatible Plug-ins Disabled"


  • Pete

    Okay, Fixed it by starting again with a clean install of letterbox, plist edited before starting All now ok.


  • Tony

    This worked for me.

    Spot on. thanks.

    I've used letterbox for so long that I cannot use mail without it

  • Philippe

    All is OK with OS 10.6 and Mail 4.4

    Merci beaucoup


  • Daniel

    Thanks a lot.

    Worked perfectly.

  • Billy

    Nice one. All is good again!

  • John

    Great stuff, back working again. Thanks for the quick fix!

  • Kevin

    Thanks for the help. Fixed it right up, first time.

  • LG

    Thank you – easy fix!

  • Joerg


    It works again.

    I wonder how you found out that fix.

    Thanks a lot

  • Jens

    Thank you so much. I knew there would be others with this problem with 4.4. Great article, easy to follow – thank you.

  • Travis Ulrich

    A Haiku:

    I can't live without

    Letterbox for Apple Mail

    Thanks a million!


  • carlo


  • Mercedes

    It works!

    Thank You

  • Debbie

    Thank you!! Question – I have several Bundles (Disabled) – is it OK to trash the old ones?

  • Niclas

    Thanks! Worked great, although it would help some if you left the … intact on the part where we're supposed to cut and paste:)

  • Niclas

    Whoops, my text got cut out since it looked like html. One more try:

    Thanks! Worked great, although it would help some if you left the (string)…(/string) (but with less/greater than chars) intact on the part where we’re supposed to cut and paste:)

  • AshR

    Very cool. Fast, quick fix that works perfectly ;) Thanks !

  • Rady Fahmy

    Worked like a charm not only for letterbox but for Omnifocus. Thanks a mil