When a user reads a message and tries to activate my Add-In, they see "You cannot perform this action. Permission to this message is restricted". I can see that the user is encrypting their messages. Is it standard for JS Add-Ins to not work for encrypted messages? Or is there a permission setting in the manifest I can use to read emails securely via the API?
The answer is over here: MSDN: Outlook add-ins on emails with digital signatures