I got a new one today: a marketer sent one of my clients a spam with a read-receipt request attached to it, then replied to the read-receipt to demonstrate he knew my client had read his spam.
The client is using an Entourage client against a Exchange 2003 SP2 system. Entourage doesn't appear to deal with read-receipt requests itself, everything I've read suggests that it is a "feature" in the server itself.
Putting aside the evil diabolicalness of such a plan, I can't seem to figure out how to prevent Exchange from responding to read-receipt requests.
I have gone through the System Manger to Global Settings -> Internet Message Formats -> Default -> Advanced, and disabled the 'allow delivery reports' field.
My user has logged on to OWA, and confirmed that in Options -> Privacy and Junk E-mail Prevention, the Do Not Automatically Respond To Requests field is checked.
How do I turn off this functionality?