SMTP Auth Logging?

[BrianZ]

I just deployed a new Plesk 9.2 server on RHEL 5.3 and migrated from my old Plesk 8 installation. While looking through my /usr/var/messages file, I do not see any entries for smtp_auth. I had read this bug was fixed in 8.6. From time to time I've had a client machine catch a virus and start sending mail and these smtp_auth logs are very handy to track those down. Can someone tell me how to enable this logging or direct me to the appropriate logs? Thanks for your help!