Not sure if this is the case here.. But I've received some emails as 'undeliverable' to my own email address that I never sent out. They are a result of someone's system being infected with a virus .. W32.Klez.e
This W32/Klez variant has the ability to spoof the email from field. The senders address used by the virus, is one that was found on the infected user's system. Thus, it may appear that you have received this virus from one person, when it was actually sent from a different user's system. Viewing the entire email header will display the actual senders address.
The virus can also send mails with empty Subject and/or body.
This virus can also unload several antivirus programs from memory
Info on the worm