I’m trying to get a better understanding of the relationship between relay and transport.
In the standard config on an email gateway in (http://www.postfix.org/STANDARD_CONFIGURATION_README.html#firewall) the proposed config has relay_domains set for example.com and transport_maps set to a hash with example.com using smtp:[inside-gateway.example.com]. My question is, how is this functionally different from setting relayhost to [inside-gateway.example.com]? Are transport maps used to replace relayhost when more granularity is needed? And how does this configuration indicate that outbound email should be delivered directly? Just that it’s not in the relay_domains list? If I wanted email to my domain to go to and internal gateway and email to the outside world to be delivered directly, is it the lack of a * entry in the transport_maps hash file that tells the server to look up the MX record and start attempting deliveries to those servers? I’m sorry for such n00b questions. I thought I knew a fair bit about SMTP but with SO many parameters I feel like I’m suffering an information overload nervous breakdown trying to figure out how to set up my environment. Thanks, Scott
