Ignoring MX records - how common

Mark_Andrews at isc.org Mark_Andrews at isc.org
Tue Feb 11 01:49:06 UTC 2003


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> Mark_Andrews at isc.org wrote:
> > 	
> > 	It will be SPAM unless one of your nameservers is returning
> > 	NODATA to MX requests.  You have to have a negative answer
> > 	to the MX query before you make the A request.  Nameserver
> > 	failure is *not* enough to cause fallback to A records.
> 
> Mark, you're assuming things all follow the RFC's, my question
> is how many don't.

	Why do you care?  All such MTAs are BROKEN.  The best thing
	you can do with a broken MTA is to not accept mail from it.
	The best way to do that is to not run a SMTP daemon unless
	you are expecting to receive email.

	People pandering to broken software results in the continued
	use of broken software.  This in no good for anyone.

> So far most stuff is spamware, but there are 2 distinct genuine
> servers doing this (since one belongs to a DNS consultancy you
> never know if their DNS is "fully debugged") to me.

	Well you are doing them a disservice by accepting the email.
	
 
> I have found reports of Hotmail, and also IIS SMTPSVC doing this
>  with form mail, but I can't confirm either as I don't regularly
> get mail to the domain in question from either of these sources.
> Beside if it claimed the sender was on hotmail I'd probably
> assume it was spam without double checking.
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--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org


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