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

2020-09-28 18:11:39

On 29 Sep 2020, at 08:44, John R Levine <johnl(_at_)taugh(_dot_)com> wrote:

(There are already some IPv6 only ISPs and I expect this will become more 
viable over time.   Should they have to set up IPv4 tunnels or ALGs for 
their "legitimate" customers so those customers can still send email to IPv4 

No, they need a fixed IPv4 address with an MX so people on IPv4 servers can 
send mail *to* them.  As we've said a few dozen times already, one mail 
server on one IPv4 address can handle a whole lot of mail for a whole lot of 
people, both inbound and outbound.

The usual word for one-way mail to which one cannot reply is "spam”.

And if you have a IPv6 address that is reachable it is not “spam”.  Out bound 
address do not have to
match in bound addresses.  Remember this is delivering email to legacy 
addresses who may well end up
having a smart dual-stacked host for outbound traffic to workaround not having 

John Levine, johnl(_at_)taugh(_dot_)com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. 
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Mark Andrews, ISC
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PHONE: +61 2 9871 4742              INTERNET: marka(_at_)isc(_dot_)org

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