|Relay based on $=m
||V8.9 and above
Ordinarily, only hosts listed with RELAY_DOMAIN (Section 18.104.22.168) are allowed to relay through the local
machine. This relay_entire_domain feature allows
domains listed in the $=m class to also be
relayed, including any hosts that end in any of the domains listed in
the $=m class. This feature, how it is used, and
how it fits into relaying and spam handling are explained in Section 7.4.5.