IP listed on Spamcop, no virus detected

[Katana]

The IP address where I work was listed on Spamcop due to viruses sending spam from one of our PCs. I found some viruses on one PC yesterday and removed them. The Spamcop listing was supposed to expire last night after I had left, which it did, but when I returned today it had been listed again. I checked the PC that had the viruses with AVG and Kaspersky and nothing was found, I also checked every other PC on the network with both AVs and still nothing. Anyone have any idea what else I can do to find what is causing this?


edit: sorry, just noticed I posted this in the wrong forum, I meant to put it in Tech Support

 

[sourceninja]

It could be that simply people are reporting again, even though you are not sending.

Guys like me who don't check our inboxes. Or delayed mail deilvery, etc.

 

[jfall]

You can signup to spamcop to receive reports about your network. It will show you the message(s) that caused the block, so you can determine how to stop it. See http://www.spamcop.net/fom-serve/cache/94.html for more info

 

[nweaver]

I fire up a big heavy gun like NTOP and watch what's leaving my network, so I can find the offending box. Also good for scaring employees into not abusing the internet (since you can show them how you can see exactly what sites they are visiting, etc) even though it's not very practical to run 24/7 imho