I upgraded a RedHat 9 e-mail server with about 500 clients on it, from Postfix 1.3 to 2.0.19
The upgrade is generally working, and clients, both POP & IMAP, can get mail from inside domains and outside domains. Clients can send to each other, but cannot send off the server
the mynetworks = and the mydestinations = worked with the 1. version that came with RedHat9. (and relay_domains = $mydestination as well).
The clients with difficulties are all behind a firewall, on a 10. network, coming through the firewall with NAT to the mail server. The server is not yet behind the firewall, and for domains we serve that don't come through the firewall, sending is ok.
There is a config variable proxy_interfaces = but the instructions are unclear as to whether that is the outside of the NAT, or the inside network, and without a better description of its behavior, I'm not sure of its relevance. The server provides service for a number of domains, many of whom come through firewalls, but we are not a secondary MX -- we're their only MX.
I'll appreciate any thoughts on this anyone might have.