[Mimedefang] IP Reputation data collection (announcement, Internet draft)

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--- On Fri, 4/30/10, Dave O'Neill <dmo at roaringpenguin.com> wrote:
> > 7 - invalid MX records
> 
> That's not terribly useful for a sending IP address, as
> there's no legitimate reason the sending IP needs to be an
> MX of the sender's domain.

I don't think that's what he had in mind, and it certainly isn't the first thing I think of when validating an MX record.

Blocking MX records that eventually resolve to localhost or documentation addresses (or don't resolve at all) is what comes to mind first.