Re: Why smtp instead of relay?

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Why smtp instead of relay?
\ Etienne Pretorius (16 May 2007)
. \ Victor Duchovni (16 May 2007)
. \ Noel Jones (16 May 2007)

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Subject:	Re: Why smtp instead of relay?
Group:	Postfix-users
From:	Noel Jones
Date:	16 May 2007

At 09:56 AM 5/16/2007, Etienne Pretorius wrote:
>Hello list,
>
>I need some clarification, you see I am trying to configure a
>machine to relay domains I host to the pop server via the relay
>daemon while still being able to smtp out any emails I receive from
>$mynetworks.
>
>As far as I understand it, postfix should accept emails that match
>$relay_domains and it does but the document
>(http://www.postfix.org/postconf.5.html#relay_domains) continues and says that:
>
>"Domains that match $relay_domains are delivered with the
>$relay_transport mail delivery transport. The SMTP server validates
>recipient addresses with $relay_recipient_maps and rejects
>non-existent recipients. See also the relay domains address class in
>the ADDRESS_CLASS_README file."
>
>Well I took a look and on my system the $relay_transport = relay. So
>I thought that since relay is a copy of smtp that I'll just add the
>relayhost directive to the pop server and that should solve my problem.
>
>master.cf:
># When relaying mail as backup MX, disable fallback_relay to avoid MX loops
>relay unix - - - - - smtp
> -o relayhost=[ip.add.re.ss]
> -o fallback_relay=

The relayhost parameter is used by trivial-rewrite, not by smtp, so
including relayhost as an smtp option has no effect.

If your goal is to have all relay_domains routed to a specific IP, simply use
# main.cf
relay_transport = relay:[ip.add.re.ss]

If your routing needs are more complex, then use transport_maps
entries to define where various domains are to be routed.

>May 16 14:41:46 postfix/smtp[25439]: warning: host
>SENDERMX[SENDERMXIP]:25 greeted me with my own hostname

Note that both the relay and smtp transports will log as
"postfix/smtp", since it's the same program.
If you need to override the "greeted me with my own hostname" error,
you can change postfix's idea of the hostname by added '-o
myhostname=local.example.com' to the relay transport definition.

--
Noel Jones