[Mimedefang] sending relay has no MX record?

Sven Schuster schuster.sven at gmx.de
Mon Jan 31 09:39:37 EST 2005

Hi Lee,

On Mon, Jan 31, 2005 at 08:26:43AM -0500, Lee Dilkie told us:
> I think Gary asking something different. He wants to check if the "from"
> domain has an MX record.
> I think this is a valid test, as how could you send an NDR to such a
> domain, and a simple "reply" obviously wouldn't work so well.

consider someone using a dyndns provider and then using a sender
address of xyz.homelinux.com for example. This domain probably won't
have an MX record in DNS. In this case mail for xyz.homelinux.com
will be sent directly to the host xyz.homelinux.com.
Of course one should not consider sending mail with a dyndns from-
address as there's a small window after assignment of a new ip
address in which email delivery to xyz.homelinux.com will be tried to
the old (but in the meantime maybe newly assigned) ip address because
the DNS database isn't up to date yet.


> I wouldn't think you'd get many hits on this sort of test, anyone who's
> gone through the trouble of setting up a domain has probably also
> defined an MX record. But let us know if you do get any hits, I'm curious.
> -lee

Linux zion 2.6.11-rc2-mm1 #1 Fri Jan 28 18:13:44 CET 2005 i686 athlon i386 GNU/Linux
 15:28:54 up 2 days, 21:10,  1 user,  load average: 0.00, 0.03, 0.00
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