I'm implementing a MEMessageActionHandler Mail extension on macOS 26.4.1 (Xcode 26.4). The extension is discovered by Mail and appears in Mail > Settings > Extensions, but Mail shows only an "Uninstall" button — no enable toggle. The MailKit consent dialog asking permission to process messages in the background has never appeared. Console logs show optedIn: NO /
userEnabled: Not Enabled.
Extension Info.plist (key parts):
<key>NSExtensionPointIdentifier</key>
<string>com.apple.email.extension</string>
<key>NSExtensionPrincipalClass</key>
<string>CheckThisMailExtension.MailExtension</string>
<key>MEExtensionCapabilities</key>
<array>
<string>MEMessageActionHandler</string>
</array>
Principal class:
class MailExtension: NSObject, MEExtension {
func handlerForMessageActions() -> any MEMessageActionHandler {
return MessageActionHandler()
}
}
Entitlements: app-sandbox: true, application-groups: [group.com.xxx]. App is Developer ID signed and notarized.
Has anyone successfully gotten the consent dialog to appear for MEMessageActionHandler on macOS 15/26? Is there something beyond the standard template configuration that enables it?
Any entitlement that needs to be provisioned separately?