Possible Duplicate:
Spam coming from domain, but from a user that I don’t have
How to stop people from using my domain to send spam?
For weeks I've been getting 10-20 delivery failure notices a day. Somebody has chosen one of my domain names to sell Viagra. I immediately checked to make sure I had my SPF records in place, and they were there not - so I added them. Doesn't seem to have slowed anything down, though.
It sucks because at this point, since my addresses have "sent" so many, I'm receiving one spam email every 45 seconds, 24/7.
Is there any other option I may have?
as you've already setup the SPF record and the spammers have used your domain, it is very likely that you'll be receiving failed delivery notifications for a while now.
I would recommend to setup a spam filter rule to discard the the messages that has anything related to content of spam emails sent using your domain name.