Two days ago I started receiving a flood of mailer-daemon/postmaster emails stating an email could not be delivered. They are spam emails that I am not sending out, nor do I have a virus on my network sending them out. My concern is that I will eventually be placed on an RBL and never get legit email out to my clients. Is there a way to stop this? I can not really find out who is sending the email since the headers are showing the postmaster IP and not the actual original sender. It seems the person is sending the email from a program called "SquirrelMailer". Any suggestions?
