> On Nov 12, 2019, at 3:52 PM, Bill Cole
> <[email protected]> wrote:
>
>> For the record, it is NOT an RFC violation for the EHLO name to
>> differ from the name in the PTR record of the connecting IP.
>
> Right and as was stated & I affirmed: it is explicit in RFC5321 S.4.1.4:
>
> An SMTP server MAY verify that the domain name argument in the EHLO
> command actually corresponds to the IP address of the client.
> However, if the verification fails, the server MUST NOT refuse to
> accept a message on that basis.
The correct way to verify that would be to resolve the EHLO name to
an address, NOT to resolve the address to a name. This would then
find no anomalies with:
Received: from ehlo.example (ptr.example [192.0.2.1])
when ehlo.example also resolves to 192.0.2.1.
--
Viktor.
