Read receipts have been around for ages in Outlook with Exchange. It’s never reliable and annoying, and I thought it only seemed to work internally. However, that must have been changed lately, since I’ve seen read receipts sent out without a person’s knowledge. I even had a user coming to me asking why she kept getting this person’s out-of-office message every time she opened one of his emails. After a mail trace, it seems obvious that this person requested read receipts from all his emails. With his OoO on, any read receipt he receives triggers an Out-of-Office message back.
Creepy as hell, so I decided to put a stop to this by adding a Transport Rule that drops any read receipt right there.
Go to the Exchange admin center, and Rules under Mail flow. Click Add a Rule to create a rule with the following conditions,
- The recipient is external, outside the organization, and
- The message properties include the message type ReadReceipt, and
- The sender is inside the organization.
and do the following action,
- Block the message and delete the message without notifying anyone.
I’d suggest adding a Generate incident report action for a period of time to make sure the rule works the way you designed.