I have a qmail server running w/o relay (default). I sent an e-mail to someone and I mistyped the address. As normal I got a failure response due to the e-mail account does not exist.
What concerns me is that in the "To:" field the failure response came from "firstname.lastname@example.org"@mail.[mydomain].com...
I have been around enough to know that the email@example.com
should NOT be part of this domain. I have checked my server to ensure it is not an open relay, which I'm glad to say seems not to be.
However, I'm concerned that someone has compromised my server and got around Qmail's open relay block. Second, I would like to know which file I need to edit to remove this richard fella for good.
Any assistance from you would be greatly appreciated.