You can try to restore compatibility with the updated Mail.app by changing which UUIDs your plugin is listed as being compatible with. This does not guarantee a fix since aspects of the updated Mail.app might actually be incompatible with your plugin.
- Make sure Mail is closed.
~/Library/Mail/Bundles (Disabled [x])/[Name of Plugin]/Contents/Info.plist
I recommend using TextWrangler
- Then add the following strings to the SupportedPluginCompatibilityUUIDs array:
It should look something like this when you’re done:
- Finally move the plugin(s) you altered from the “Bundles (Disabled)” folder to “Bundles” and open Mail.app.
If the plugin breaks Mail.app move it back to the disabled folder.