[SLL] Multiple domains on postfix/dovecot

[Chuck Kranz]

Hi All,
I have a CentOS 5 node that I would like to host multiple domains on.
I have each domain configured on DNS with it's own mail exchange.
The users are able to login and read their mail but can't send.
I've got a minimal postfix configuration with the domains listed
in mydestination
When they try to send it get gives the error: The server is not available
or not giving connections.
  What kind of config do I need?
Thanks,
-Chuck