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postfix-users: Seeking clarification on XCLIENT and XFORWARD

Seeking clarification on XCLIENT and XFORWARD

From: Patrick Ben Koetter <p_at_nospam>
Date: Thu Oct 07 2010 - 11:33:48 GMT
To: Postfix Users <>

I understand a server announcing XFORWARD is ready to accept session META data
acquired from another client, but I don't understand where XCLIENT fits in.

>From my understanding a typical XFORWARD situation would be data (IP, hostname
etc.) from client that talked to Postfix is passed by Postfix to another SMTP
server e.g. amavis. The data would enable amavis to make useful decisions e.g.
DNSBL lookups or choosing an apropriate policy bank etc. In this case amavis
implements XFORWARD and forwards it. Am I correct?

Is XCLIENT a variation of XFORWARD or is it the other side of the medal,
meaning e.g. it sets the policy to which server announcing XFORWARD Postfix
may pass client information?


-- All technical questions asked privately will be automatically answered on the list and archived for public access unless privacy is explicitely required and justified. saslfinger (debugging SMTP AUTH): <>