What is going on??? I receive anywhere from 15-30 of UNDELIVERABLE / MAIL DEMON FAILURE / UNKNOWN ADDRESS return mail messages on a daily basis. Is this a virus situation or related to flagging and reporting several unwanted emails as SPAM? I did not have this problem until approximately one month ago. Hope you can help.
Spammers frequently spoof return addresses when sending out mass mailings to randomly generated addresses. But given the sudden increase in your bounced as undeliverable email, it may be that someone with your address in their address book is infected with an email virus.