Newbie question

I was searching for open source mail server and i was trying zimbra but that was useless,some errors. And i found Axigen. Looks awesome. I woild like to ask regarding experience with it?
We have 20users one domain.
We get a lot of spams even with spam filters and viruses with proprietary mail server And i would like to move to open source.
Please share you experience.
Graylist,manual rules,mail forwarding delivery if a person leave company,spam filter dns usage,IP bans/restriction per user(for some local smtp is enought) and good logging
Thank you.

You will change your mind if have experience to work with axigen.
very light and too fast service, safe and secure, ease of use with very nice interface for users and admins, expert support team and etc.
There are some tips in axigen that you can reduce receiving spams without antispam and antivirus over 70% and with AV & AS over 99%.

Thank you very much for your comment.
On regards of the reliability sending/receiving, small/big/non-issue?
How many users you have?

ohh damn, the free version have limitation D: