Do some spammers ignore MX ptrs?

[Jeff A. Earickson]

Hi,

If your A and MX records don't match for your domain, then AOL will
rate-limit your email to them.  I recently went thru this experience
when I moved my mail service and goofed on DNS.  It was painful.

Jeff Earickson
Colby College

On Thu, 27 Apr 2006, Michael Masse wrote:

> Date: Thu, 27 Apr 2006 08:30:07 -0500
> From: Michael Masse <mrm at medicine.wisc.edu>
> Reply-To: MailScanner discussion <mailscanner at lists.mailscanner.info>
> To: "<MailScanner discussion" <mailscanner at lists.mailscanner.info>
> Subject: Do some spammers ignore MX ptrs?
> 
> I'm offloading just Mailscanner services from an overloaded email store
> machine to a new machine and am doing so by pointing the MX record for
> the domain to the new machine.   The A ptr still points to the old
> system so that none of the other services this machine provides get
> interupted.     All legitimate email and most spam is going to the new
> system like it's supposed to and it then gets relayed to the old store
> machine, but I'm noticing quite a bit of spam is still being sent
> directly to the old system.     Does some spam software ignore the MX
> ptr and go to the A ptr instead, or is this more likely to be a DNS
> cache issue on the sending systems that will hopefully clear itself out
> over a few days?
>
> Mike
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