Right. The from feild is spoofed, therefore it gets sent back to you. I've gotten so many back it isn't funny anymore. The headers indicated the source IP of some, so I did send a PM to that person.
Even though your system is clean, you can still get these non delivery reports.
Yup. That was the case here. I thought the Email I got was from you but the IP address revealed where it actually came from which wasn't you.