spoofed or pc infected

For about 2 weeks now i have been receiving "Undelivered Mail Returned to Sender" messages, on a business email address which i need to keep. On average 1 a day.

I am very security conscious. I use za pro, ewido, ms anti spyware, ad aware, spybot, pest patrol, and my pc has just been scanned with symantec online scan and panda's online scan. All scans report a clean system.

So i don't think my pc is infected with malware and is serving spam. I think some scum spammer has decided to put my email address in the return address field of their mails. I have been getting spammed on this address for a long time now, but i've never had this Undelivered Mail Returned to Sender problem before. All the actual spam is caught by spam assassin on the server, or cloudmark's outlook plugin. obviously the undeliverables are not.

Can anybody offer an opinion on what is happening? Could it be that all these scans have missed a spam server installed on my pc?

 

This could be a direct mail to you, attempting to get you to open the messages. Or it could be due to someone's email getting compromised, having your address in their address book. I get them too, and just send them to the bit-bucket.

 

They have attachments and unfamiliar recipient addresses, don't they? The intent is for you to let curiousity get the best of you so you open up the attachments. Add them to your junk filter.

 

Well no. a lot of them don't have attachments. one of them had and it was a virus, but avg had killed it before i got near it.

another had a plain text attachment, which i saved, then scanned with every scanner i've got, and then openend. it did contain a link which i checked out. it did not seem to be dangerous, although i was using firefox with javascript and java disabled, so maybe it just couldn't touch me.