guys, i have a similat issue here, my domain mydomain.com had a PUBLIC IP x.x.x.x then me and the ISP changed it to y.y.y.y for some other reasons, so i had to change my PPOE IP Address in my CentOS 5 Box to y.y.y.y to match the new address for my domain.
now mails are no longer moving, i chaked the log and saw:
it seems like its trying to bind to the OLD IP Address that i changed from.
Dec 15 10:44:54 mcpserver postfix/postfix-script: starting the Postfix mail system
Dec 15 10:44:54 mcpserver postfix/master: fatal: bind [B]x.x.x.x [/B]port 25: Cannot assign requested address
Dec 15 10:44:55 mcpserver saslauthd: detach_tty : master pid is: 7019
i edited the /etc/hosts and added the new address y.y.y.y
then went to the zone file in my DNS Config and removed the OLD IP and out the new Address,
where else might be the problem? since its trying to bind to the old address?