This is using a single MS Exchange 2010 server in Windows 2K8 R2 AD domain. I am using exchange native anti-spam feature to stop spams from coming in. On the block list providers, I am using bl.spamcop.net and zen.spamhaus.org. As for the SCL, 9 is deleted, 8 is rejected, and 6 for quarantined. Others, such as, sender id, sender reputation, not implemented as no idea.
However, users kept on receiving spams, and mail with spoofing addresses. The only to do was checking the message header for sender IP, and then blacklist them. Please advise how can increase the efficiency and accuracy of the anti-spam.
thanks in advance.