At least he got a warning
I once had this problem when a supplier I was dealing with finished an email with "if you have any questions cum comments...": a perfectly legitimate word in this context. After repeatedly chasing the supplier via email for the information I was waiting for I called my contact only to be told that he'd been responding to each chase by resending. We both spoke to our helpdesks to track down the problem and found that my end was binning the email without telling either the sender or recipient of what it was doing. Not helpful. I can understand not telling the recipient, thus avoiding annoying someone who is being spammed, but tell the sender, and if it is spam: who cares if we spam them back?