When our system detects a SPAM message it will insert [SPAM] into the subject.
The email system uses the popular Bayesian filtering in order to detect and mark spam. The threshold is set to 90%, so the system has to be 90% sure the mail is spam before inserting [SPAM] into the subject.
Currently the system operates a global SPAM policy, in future we will develop it so you can customize the spam settings on a per mailbox basis.
We operate fairly relaxed DNSBL (DNS Blacklist) rules which can help block known spammers, and although the system recognises SPF records – we dont utilise them to combat spam.