I came across an issue which surprisingly i could'nt find any post related.. I am running a centos server with postfix which is being used as an outgoing mail server.

The sender_blacklist and mynetworks allow a certain foreign exchange server to send through this outgoing server. The problem occurs when the exchange server is trying to send messages which are actually a forward action, therefor it is identifying the sender as the original sender and not the "forwarder".

Note: The sender_blacklist includes the original sender's domain as reject (like yahoo)

I've tried creating a new hashed-file which runs in the tops lines of main.cf which includes the sender's IP as allow, but this still does'nt bypass the reject at sender_blacklist.

My question is: How can i allow a certain IP to spoof? (maybe using a hashed-file which will apply firstly, and by that override the sender_blacklist which blocks specific domains)

Any idea would be appreciated..