I am running a Plesk 9.0.1 Web Server on Ubuntu 6.06.2 LTS and have about 100 small to medium web sites hosted on the server. The problem is that I believe one of the websites has a script that is allowing spam to be sent through the server. The reason I believe this is that I get 1000s of messages an our deferred in the mail queue that show to be sent from the www-data user.
My question is if someone can tell me how to find the script or scripts that is sending the SPAM?
Thanks in advance for your help.