What I like best about SpamTitan is having a simple online interface where we can monitor in realtime the emails coming through the system. SpamTitan blocks persistent emails by domain or email address and whitelists email addresses is easier for all users. At any point emails can be released to the user and daily summary makes it great for the user to highlight any false positives. I've not had an issue with the system since going live 12 months ago.
I recommend anyone to use the free trial to see if it compatible with your needs first. This gave us total confidence that it was going to meet our needs. I like the easy access to the spam filer, quarantine and users. If a new client has emailed and we have not received the email we can easily check the filter first. Their email can then be whitelisted. We have been able to bypass our external IT support and have one main user who can control this in house saving so much time.