The anti-spam agents in Exchange Server 2007 log their actions in agent logs. By default, agent logs reside in \Exchange Server\TransportRoles\Logs\AgentLog. Each agent log is 10 Mb in size. The size of the directory is capped at 250 Mb, the age of a log to 30 days. (Logs are flushed when they "age" up to 30 days or if the directory size reaches 250 Mb - whichever happens first).
