MailPluginFix will help you to fix any incompatible Mail.app plugin after an update of OS X. It patches all broken plugins with the current UIDs and also enables them again.
- Added support for macOS 10.12 Sierra. Important: macOS 10.12 is a major update and many mail plugins are not yet compatible with the new Mail.app. Before trying to fix a plugin, check for an official plugin update and don’t forget to backup!
- Added toolbar button for opening the Mail library folder
- Fixed info-window width
- OS X 10.6 or later