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Fixing disabled bundles/plugins for Mac Mail

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I confess (not that you might not know, but still…) that I am a mac user. I have been for some time now and I quite like it. As such I have got used to using for checking my email although I am well aware that it is by no means the best email client ever. Nonetheless, I do use it, and I do in conjunction with some useful plugins such as TruePreview and Universal Mailer that help improving the experience. TruePreview lets me scan an email without marking it as read, whereas Universal Mailer removes some annoying ATT00001.htm files that recipients get and correctly formats messages with attachments and inline images. They both work quite well… until Apple decides to upgrade the and disables the plugins. One thing that you can do when this happens is to shake your fist in the air, curse a bit and wait until the plugins get updated. Or… you can try this and hope that the plugin starts working by adding the correct Universally Unique Identifier, or UUID, to the plist file. Here is how and please note that the UUID values quoted are valid for 6.6 (OS X 10.8.5):

  1. Quit Mail
  2. Open Terminal
  3. Type: cd Library/Mail
  4. If you request a list of the files (using ls) you should see a folder like “Bundles (Disabled)”
  5. Type: cd Bundles (Disabled) – Note that the folder may be numbered, so check the contents…
  6. If you are trying to fix TruePreview then type: cd TruePreview.mailbundle/Contents
  7. If you are trying to fix Universal Mailer then type: cd UniversalMailer.mailbundle/Contents
  8. This may also work for other plugins… so check the correct folder.
  9. Once you are in the correct folder for the plugin, type: open -e Info.plist
  10. The command will launch a text editor and you will be able to edit it. Go towards the end of the file and add the following lines:


With the recent release of Mavericks, the application is currently version 7.0. The correct strings to use are as follows:


Please note that although the above strings make Mail accept plugins such as TruePreview, the functionality does not work. 
In the case of Universal Mailer, there is an update for Mavericks here.
Once that is done, save the file and close it. Back in the Terminal
  1. Type: cd ../..
  2. Now we need to move the “Disabled” plugin to the working folder. For TruePreview type: mv TruePreview.mailbundle ../Bundles
  3. A similar command can be used for other plugins
  4. Finally, launch Mail
  5. And Voilà

So, what happens next time that the Apple gods decide to update Mail? Well, you can obtain the correct UUIDs as follows:

defaults read /Applications/ PluginCompatibilityUUID

defaults read /System/Library/Frameworks/Message.framework/Resources/Info PluginCompatibilityUUID

Each of them will return a two different strings that are the new UUIDs for running under. You then need to add those strings to the info.plist file as explained above.

This may come handy when Mavericks is finally out… Then again, things may have changes a lot behind the scenes…

Let me know if you have found this tip helpful!


21 thoughts on “Fixing disabled bundles/plugins for Mac Mail”

  1. Brilliant! This fixed Universal Mailer for me and I’m hoping your bit at the end will mean I won’t have to scramble with each Mail update. Cheers!

  2. Hey, thanks for the tip. One question: If I try to edit the file info.plist I got a message that I’m not the owner of the file and that I cannot change it. What shall I do? Thanks for your answer. Best wishes, Marcel

    1. Hello!
      To change the ownership of the file you can use the command chown. You will probably need superuser (admin) access. I recommend that you check the web for using the command.

      Quantum Tunnel

  3. Thanks, this was perfectly helpful..

    Being a former PC user I’m always disappointed of OSX when I have to hack the system because of Apple…

    Thanks again

  4. Thanks, this worked very successfully. I also used the same method for GrowlMail, MailActOn and MailTags.
    Your instructions seem unnecessarily complicated though, I can’t see any reason to use terminal for this, Finder will work fine.

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  6. Unfortunately, TruePreview doesn’t work with Mavericks Mail. The plugin appears in Preferences, but it’s not working.

    1. Hello, you are right, the plugin is accepted but the functionality is thwarted… Oh well, I guess we all will have to wait for the developers of TruePreview to update the plugin.

  7. Worked perfectly before Maverick came out. Used the new string… but no luck. Have you checked that it is still working with Maverick?

    1. Hello JF,

      thanks a lot for the comment. You are right, the plugin is accepted by Mail, but it does not function as expected. As I mentioned to Wotjek, we will probably have to wait for an update from TruePreview themselves.

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