| More than like one of what has been said above, I'd go with someone else is spoofing your address though. Basically someone out there, a friend etc has you in their contacts and emails are being sent from what looks like you from there account, the NDR's (non-deliveries) are being returned to what it believes is the senders address - YOU.
A long shot would be to contact everyone you have regular emails to/from and ask them to uodate their AV definitions and scan their machines |