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

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--- On Fri, 4/30/10, Kevin A. McGrail <KMcGrail at PCCC.com> wrote:
> 7 - invalid MX records

This is the only one I disagree with as it can be detected on the fly if one really wants to, and if someone alters their DNS RRs to be correct, relying on the DNS data would mean "delisting" as soon as any DNS caches time out thus resulting in the new, valid data.

If it turns out that your DNS overhead for checking the MX records takes too much time, then greylist the mail and continue the DNS fetches in the background, so the info should be cached and thus instantly available at the first retry.