Email Engagements allows the ability to follow emails. This only happens automatically when sending emails directly from Dynamics. When a user is in App for Outlook, this has to be done manually, only after you have selected to track this record. If you use any type of automatic tracking for incoming or outgoing emails or have built any process to automatically set regarding, to make user interaction more simplified, this would still require them to manually Follow the email. We should have the ability to automatically follow emails sent from Outlook.