When you edit a user profile as admin, there is the checkbox missing: "Mass mailings: Subscribe to emails sent out to all users"
I often have returning emails from email servers that stated, user does not exist, or alike. Then I need to unsubscribe them. Since the email body with unsubscribe link is often not send back, I have to dig into the databse to find the user, then change the flag bitwise... just a hassle.
Thanks for consideration.
qa_db_user_set_flag($loginuserid, QA_USER_FLAGS_NO_MAILINGS, true);