I use postfix to send direct email. But, I use a relay to send email for specific senders. So I use "sender_dependent_relayhost_maps" :

/etc/postfix/main.cf :

relayhost =
transport_maps = hash:/etc/postfix/transport
smtp_sender_dependent_authentication = yes
sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay

/etc/postfix/sender_relay :

[email protected] smtp.relay.com

So when I send an email with sender email "[email protected]", postfix will use the relay.

But... I don't want to use the relay host for some recipient. ;)

I think I must use "transport_map" to catch the email before it pass through "sender_dependent_relayhost_maps" but I don't know how to do it...

Thanks