in macOS 10.11 and earlier used to check the plugins compatibility using the SupportedPluginCompatibilityUUIDs key in the plugin’s Info.plist. For example a Mail plugin would only be compatible with macOS 10.11.6 if its Info.plist contained the following:

  • Easily preview Mermaid diagrams
  • Live update when editing in your preferred editor
  • Capture screenshots with customizable margins
  • Create PNG from the Terminal
  • Free download on the Mac App Store
</array> version 10.0 in macOS Sierra (10.12) now uses a different key to check the plugins compatibility. It now requires a key with the format Supported%ld.%ldPluginCompatibilityUUIDs where %ld.%ld is the operating system version like “10.12”.

If you want to make your plugin compatible with macOS Sierra, you will need to add a key in your Info.plist like:


Note that the UUID “36CCB8BB-2207-455E-89BC-B9D6E47ABB5B” is for macOS Sierra 10.12 beta 3.

Also by default the Mail plugins support is disabled. In order to enable it you first need to run in the Terminal the following:

defaults write EnableBundles -bool true

Related post: Disable swipe to delete in on OS X 10.11