proxy_interfaces understanding

3 msg	Server configuration Error
1 msg	relay_transport
1 msg	Catch-all mailbox
4 msg	Trouble with HTC S710 device and SMTPS
3 msg	psotfix server TLS failed
3 msg	failed-delivery message notifications setup

proxy_interfaces understanding
\ Joseph L. Casale (16 Jan 2008)
. \ Victor Duchovni (17 Jan 2008)

1 msg	warning: transport virtual failure
2 msg	how to relay for most recipients and forward fo...
2 msg	Rewriting outbound addresses
2 msg	virtual mailboxes/domains and aliases
3 msg	Enforced TLS Success?
1 msg	Postfix 2.5 RC2 and snapshot release
11 msg	Problem with Postfix and LDAP (SSL / TLS)
4 msg	More on Enforced TLS
3 msg	delivery reciept
4 msg	How to repeat delay_warning_time messages ?
2 msg	sender notification
5 msg	Using 'nolisting' to reduce spam
1 msg	mail priority by sender

Subject:	proxy_interfaces understanding
Group:	Postfix-users
From:	Joseph L. Casale
Date:	16 Jan 2008

Hi,
If postfix runs as a gateway without local mail delivery and merely forwards mail to my real mailserver while sitting behind a NAT device I see I should have proxy_interfaces configured with the real external IP. I am trying to understand what postfix does internally with this info and can't seem to find any documentation that states anymore then this will prevent mail loops when used on a backup mx server.

Can someone point me in the right direction?

Thanks!
jlc