Smart-ISP Configuration for Postfix.

note: This is another 'no-brainer, don't forget this again' type post, but I thought i'd put it here incase anyone else can make use of it.

Recently, I was told that a client needed to forward all their corporate mail via their local ISP and that I should set that up for them using their existing, internal-only mail handling Postfix server.

The key additions to their /etc/postfix/main.cf file was (aside from configuring SASL, which you should do anyway and setting the relayhost parameter correctly) was:


+++ mydestination =
+++ local_recipient_maps =
+++ local_transport = error: no local delivery service


and:


+++ myorigin = the outbound domain name you need.


Then, you need to comment out (with a #) the local transport method in your /etc/postfix/master.cf file.

Remember that, brain!