Is my computer being used for spam?

[Kuroyama]

I've noticed that periodically in the list of active icons in the lower right corner of Windows XP a small mail icon appears, with the address "host18-14.pool212171.interbusiness.it". Googling interbusiness.it I find this is a prime source of spam. I've run spybot, microsoft anti-spyware, and Avast antivirus and none of them detect anything abnormal. However, I do have port 6881 open for Bittorrent. Could it be that someone is using that port to access my PC and send out spam or something? If so then what can I do about this, other than getting rid of my Bittorent uplink?

Solved: Seems that Avast! Antivirus downloads its updates from this site.

 

[mgob]

do a 'netstat' in the cmd prompt and see if there are a lot of connections

 

[Kuroyama]

There are tons of them, but I think those are just the people being served up by my Bittorrent client.