It’s time again to circumvent Apple’s Mail Plugin policy and update the GrowlMail Bundle with the correct identifier string. Otherwise, after updating, Mail will tell you it has disabled the GrowlMail plugin and will move the bundle to ~/Library/Mail/Bundles (disabled).

To amend this, follow these steps:

1. Quit Mail
2. Move the GrowlMail.mailbundle Folder back into ~/Library/Mail/Bundles
3. Enter the following two commands into your Terminal:

   defaults write ~/Library/Mail/Bundles/GrowlMail.mailbundle/Contents/Info SupportedPluginCompatibilityUUIDs -array-add "1C58722D-AFBD-464E-81BB-0E05C108BE06"
   defaults write ~/Library/Mail/Bundles/GrowlMail.mailbundle/Contents/Info SupportedPluginCompatibilityUUIDs -array-add "9049EF7D-5873-4F54-A447-51D722009310"

4. Start Mail and enjoy Growl notifications for new eMail again!