In our plesk, we have spamassassin on, and 1/ settings >> server-wide mail preferences SPF spam protection = ON DNS zones for DNSBL service = ON DomainKeys spam protection = OFF. tried this before and it caused a few problems. 2/ settings >> spam filter settings Switch on server-wide SpamAssassin spam filtering = ON Switch on server-wide greylisting spam protection = ON Apply individual settings to spam filtering = ON The maximum number of worker spamd processes to run (1-5) * = 2 The score that a message must receive to qualify as spam * = 4 Add the following text to the beginning of subject of each message recognized as spam = ****SPAM**** Now this one mailbox spam filter score is set at 3 and he is still getting spam. The problem I find with blacklists and whilelists it is for domain/email addresses only. Spammers tend to use not real email addresses. Has anyone solved this problem and what did you use? Really need help.