Relay question - ReadList.com

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Relay question
\ Matt Walsh (23 Jan 2008)
. \ (Wietse Venema) (24 Jan 2008)

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Subject:	Relay question
Group:	Postfix-users
From:	Matt Walsh
Date:	23 Jan 2008

Howdy:

I run a small website with a small cluster of machines, all on the same LAN.

One machine runs Postfix, and serves as my inbound/outbound email MTA for
ALL machines on the LAN.

I've got said machine configured for a number of things, including DKIM,
DomainKeys (using DK-milter), and SPF.

But sometimes other machines on the cluster want to send out email. This is
done programmatically from a PHP script.

Because I'm somewhat lazy, and because it seemed to work, I just left those
machines with the default sendmail stuff but configured the "Smart" relay
host to point to my Postfix mail server (using the 'DS' sendmail setting).

This works.

Almost, that is.

I've noticed that the mail from the relayed machines does not have my
DKIM/Domain Keys header stuff.

In fact as I look at the messages I see that in fact, the messages are
relayed in the purest sense of the word. It's just as if I sent a message
from one host to my Postfix server. I can see the SpamAssasin results and
everything. That's probably why the DKIM/Domain Keys business is not
happening - that must only happen on messages that are originated on the
Postfix server.

So, I guess what I *really* want is a way to just have all my servers use my
Postfix server 'directly' as a remote server, not as a relay.

Or, some way to have the desired effect of making relayed messages look just
like originated messages - with DKIM/Domain Keys and all.

Any ideas?

--Matt