As of 2 days ago, Norton (NIS 2011) has been popping up repeated error messages reporting email errors. As soon as I close one a new one pops up. None of them relate to my email address, or any activity that I am doing myself. There are a few variants:
- 550-506.1 [220.127.116.11] The IP you're using to send email is not authorised to
- Your email message was unable to be sent because the connection to your mail server was interrupted. Please open your email client and re-send the message from the Sent Messages folder
- 451 Message temporarily deferred - 
and some more variations along these lines.
I've run full scans with Norton and Malawarebytes, with no results showing. I'm using XP. I assume that I have some malware which is attempting to use my system to route spam, but I'm not sure how to tackle it. Any advice would be very much appreciated