Do some spammers ignore MX ptrs?

[Drew Marshall]

On Thu, April 27, 2006 14:30, Michael Masse wrote:
> 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?

I would suggest some and some. Once a Spammer has found your machine, they
are likely to keep sending to it.

Your best bet would be firewall port 25 to the old machine for everything
except the new machine's IP address. That will stop them and ensure that
you can safely remove/ disable MailScanner from the old machine as all
your mail will have to go via the new one.

Drew


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