Postfix Address Verification

Drew Marshall drew at
Fri Jun 29 10:26:49 IST 2007

On Fri, June 29, 2007 04:57, Seamus Allan wrote:
> I even made a point of not top posting. Guess I can't make *everyone*
> happy.

You are so right :-) The only reason I asked was that my quotes of yours
were so mangled by my web mail client they were almost not woth including.
No biggie really (To me!)

> I spent the good part of a day investigating logs and found almost
> nothing useful. I was expecting to see a point where the main (hub)
> mailserver started rejecting the (Mailscanner) Gateways probes to check
> whether a mailbox existed, as the probes are only Helo, Mail from, rcpt
> to, then a disconnect.
> Anywho, here are some log snippets for you to gander at.
> This is for a domain where is worked:
> Jun 28 02:49:24 gatekeeper2 postfix/smtpd[8702]: NOQUEUE: reject: RCPT
> from[]: 550 <user at>:
> Recipient address rejected: undeliverable address: host
>[] said: 550 Requested action not taken:
> mailbox unavailable or not local (in reply to RCPT TO command);
> from=<agassy at> to=<user at> proto=SMTP
> helo=<144209448>

That looks fine

> And this is for one where is didn't:
> Jun 28 02:49:28 gatekeeper2 postfix/smtpd[8700]: NOQUEUE: reject: RCPT
> from unknown[]: 450 <user at>: Recipient address
> rejected: Domain not found; from=<jahka at>
> to=<user at> proto=ESMTP helo=<>

This looks like a DNS problem. Are you running a cacheing DNS server on
this box? Postfix is rejecting with a temporary failure (450) as it is
having what it thinks could be a short term problem. I assume you have set
the next hop in the transport map file, have you done this using a name
record or IP address? i.e. in the file does it say:



validdomain  relay:[]

Just to make sure this isn't Postfix logging a slight red herring, can you
also let me know what you have under:



The other thing to check is the logs of the internal machine (Exchange?),
just in case there is anything obvious there.


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