AntiVirus Mail Gateway (192.168.20.11)
AntiSpam Gateway (192.168.20.12)
<<<<< SMTP Connector >>>>
MS Exchange (192.168.1.10, hostname: mail1,FQDN: mail.domain.com)
So far, we'are using MS Exchange 2003 server for many years, it's fine... just find one client's postfix server “HELO FQDN check" rule reject our domain.
By the way, I have checked by some antispam website to get those messages
"Reverse DNS does not match SMTP Banner" or "Your helo or sender is not FQDN"
1. "HELO FQDN" is one common Anti-Spam rule ? not PTR ?
2. What can we do ? On Exhcnage server or SMTP connector, or and AntiSpam server ?