OS X’s Mail: How to manually restore plug-in compatibility

Posted by Pierre Igot in: Mail
November 16th, 2013 • 5:56 pm

Most of the time, when Apple comes up with system updates that modify the Mail application, the changes cause Mail to reject installed third-party plug-ins (known as “bungles”) by moving them from the “~/Library/Mail/Bundles/” folder to the “~/Library/Mail/Bundles (Disabled)/” folder at launch time. This happens even if there is no known compatibility issue between the new version of Mail and the plug-in.

Macworld had a column about this a few years back, and about what you can do to manually restore the compatibility — at your own risk, of course. (Sometimes, plug-ins can become incompatible and so it’s safer to wait until the developer updates the plug-ing himself or herself.)

In Mavericks (OS X 10.9), the situation has changed a bit. Mail updates still cause bundles to be rejected, but now it is no longer necessary to update the plug-in’s info.plist file with the UUIDs for both the Mail application and the Message framework.

So there is only one process left to do. After you’ve quit Mail:

1. Enter the following line in Terminal:

defaults read /Applications/Mail.app/Contents/Info PluginCompatibilityUUID

2. Keep the UUID that this command returns in a safe place.

3. Go to the “~/Library/Mail/Bundles (Disabled)/” folder and locate the info.plist file in the “Contents” folder of the bundle for the plug-in. Open this info.plist file in a text editor. (I use BBEdit.)

4. In the section called “SupportedPluginCompatibilityUUIDs”, add a line that reads:


where “XXX” is the UUID that you’ve retrieved with the Terminal command above.

5. Save the info.plist file.

6. Move the entire bundle folder back to the “~/Library/Mail/Bundles/” folder.

Now you can relaunch Mail and it will no longer reject the “incompatible” plug-in bundle.

Before Mavericks, you had to repeat the same process for the “Message” framework in “/System/Library/Frameworks/”. But as far as I can tell, this is no longer necessary in Mavericks.

Again, I stress that, if you use this tip to restore plug-in functionality for a rejected Mail plug-in, you will be doing so at your own risk. Eventually, plug-in developers will release updated versions of their plug-ins that will “officially” restore the compatibility. But it can take a while and you don’t necessarily want to have to wait, especially if you are reasonably confident that the plug-in remains compatible with Mail.

[UPDATE: Reader Brad L. notes that there is a utility called MailPluginFix that can be used to automate the process. It's listed as Mavericks-compatible.]

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