SMTPSVC1 creating extremly large log files

[Woodworker4u]

All, I noticed our SBS 2003 root hard drive filling up rapidly over the past 2 months. The SMTPSVC1 log files are very large. I imported into excel to get an idea of how many entries and we are seeing an avg of 48,000 entries a day. I am seeing names with our domain email address that do not belong to this company. Does not seem to have errors but something does not seem correct.

Can anyone give me some assistance of where to start?

Thanks to everyone.
Michael

 

[charlie2908]

Either you are a victim of spam or you have an open relay there.

 

[Woodworker4u]

Charlie, I am in agreement but I can't seem to find the open relay based on the normal process. I have used the typical telnet process to determine and it was negative for an open relay. Any thoughts would be appreciated.

 

[Zelandakh]

Well turning off logging might be a plan - are those emails getting delivered or accepted and dropped?

 

[charlie2908]

In IIS, configure your SMTP server to only allow connections from the local machine (127.0.0.1) and any other permitted servers.
Also run an AV update and do a full scan on the server for botnets and any other virus.