North American Network Operators Group|
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RE: Mail Server best practices - was: Pandora's Box of new TLDs
> Requirement ? What requirement ? There's no requirement for > reverse DNS for email in any RFC. Not that RFCs are > ideal references > for mail operation in general. You're right, documents published by an organization whose goal is to design internetworking protocols are not the best place to find operational advice. For that you would be better to go to an organization like MAAWG which publishes this BCP: http://www.maawg.org/about/MAAWG_Sender_BCP/MAAWG_Senders_BCP_Combine.pd f On page 5 they do recommend matching reverse DNS and in Appendix A they go on to state that RFC 1912 states that all hosts on the Internet should have a valid rDNS entry. Perhaps the RFC series doesn't have as many gaps as we think. > "known-dynamic" is extremely up to debate. Frankly, > blacklisting > entire /16s because individual customer PCs have been > hijacked is > absurd, but I guess colateral damage is acceptable. If collateral damage is acceptable, then how is this absurd? Once you accept that it is better to reject good email than let bad email through, the game has changed. It may end up by destroying the business usefulness of the existing email architecture, but not without a push from someone who has a better mousetrap. > I'm not laying blame here, just pointing out that rejecting mail > from IP addresses for which no PTR delegation exists is > unwarranted, This is quite simply, wrong. It is warranted. > Don't go preaching > it as a best practice, though. Too late, the MAAWG has already published this as a best practice for quite some time. If you don't follow the MAAWG best practices then you are not a serious email operator. If email is mission critical to your business, then you really should be an MAAWG member as well. --Michael Dillon P.S. I personally have nothing to do with the MAAWG although my company is an active member.