Relay single Domain to relayhost?

[polysign]

I guess it just worked that way because the public MX record for that domain points to our servers, and not to the mail server for that client.

So all mails have to come to our server first, then get forwarded to the clients exchange server.

The moment the domain was listed in the local postfix domain.db, postfix tried to post the mail locally on the server. When I removed the domain from the list, postfix tried to send it to the MX record. As the MX record (by default, on the local server where ispcp runs) points to itself, it couldn't deliver! SO I had to change the MX record manually on my ispcp for that domain.