Seb7 - 9:58 pm on Mar 6, 2010 (gmt 0)
I recently discovered a couple machines here frequently sending out emails. AVG was up-to-date, and a complete scan was finding nothing. I happening to know this because I can see the blocks of SMTP use every 10mins in our modem log files.
One of my first thoughts was, how long has thing been going on? Our ISP had already charged us quite a lot extra for over internet usage, how much of this was SMTP?. Any teckie working at an ISP looking at traffic would already know this is happening everywhere, why do they let this happen?
The problem is, if an ISP did block this, they would not be able to cope with the large amount of support calls, and the misery put on the customers to sort it out would be quite a problem.
I do feel ISPs could easy setup an automated service that warns customers of excessive SMTP use. Or the modem they supply could easy have this function built in.
Personally, Iím still unable to find the processes within our machines which is presumably sending out spam, so I blocked port 25 on our modem. Like most people, we use web mail anyhow.