Re: [ietf-smtp] EHLO domain validation requirement in RFC 5321

Keith Moore <> Sun, 04 October 2020 09:49 UTC

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From: Keith Moore <>
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Date: Sun, 4 Oct 2020 05:49:29 -0400
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Subject: Re: [ietf-smtp] EHLO domain validation requirement in RFC 5321
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On 9/28/20 7:35 PM, John R Levine wrote:

>> Actually I expect there will be systems where just 25/<ipv4-address> is
>> statically NAT46’d to a 25/<IPv6-address> and all the outbound 
>> traffic goes
>> back through the NAT64 with no linkage to the IPv4 address except for 
>> those
>> established by the inbound connections.
> Hmmn.  I suppose that if I wanted to set up a mail system to maximize 
> the chance that my mail would fall afoul of well established 
> anti-abuse metrics and get thrown on the floor, that'd be a good plan. 

Please cite these "well established anti-abuse metrics" because they 
should not be accepted as valid without question.

If you refuse to do so, it should be assumed that they are either not 
well established or that they are not valid.   Or perhaps, they are 
themselves a form of abuse.