We recently had a contact unsubscribe from an email that was sent with a transactional send classification. This email did not have an unsubscribe link and having been seeded into the email, I cannot see a way to unsubscribe from these emails.
How could this have happened? Is there any other way for a subscriber to unsubscribe without clicking on a link?
Please check this link - it is possible they might have replied: "Unsubscribe" to the email, if you have RMM - reply mail management configured in a certain way.
This is definitely RMM as it is typically setup by default to auto handle direct replies by your recipients by searching for words like Unsub, Unsubscribe, Opt-out, etc. You can check under Admin-->RMM to confirm which values it handles. It will process opt outs for these automatically.
You should be able to check your send tracking to identify the send where the opt out occurred (they are tracked under Unsubscribed which is clickable).
Else, write a simple SQL query to pull out the _Unsub table where match occurs on your recipient.
