Postfix Forward Through Relayhost

[Evan F]

I've given up on trying to filter mail through my own server, so I'm running everything in and out through Logicnow Max Mail. Each domain in Max Mail is given it's own outbound smtp relay, which I have configured in postfix via sender_dependent_relayhost_maps for each respective domain. This works great, except when a mailbox is configured to forward to another address that is not hosted on our server. When a message is forwarded, postfix is attempting to deliver the message directly and is not running it through the relay.

Does anyone have any ideas on how to get postfix to also forward mail out via the correct relayhost?