Douglas Otis wrote:
Use a host-name convention. This would be apparent at the
EHLO without requiring negotiations. In essences,
_dkim.mx01.example.com makes an assurance that:
1) this host-name will authenticate
2) a DKIM client policy can be applied
Some minimal negotiation might be still necessary, the server
could reject the underscore in the EHLO as 2821 syntax error,
based on "sub-domain = Let-dig [Ldh-str]", an underscore is no
<Let-dig>. Depending on how the server does this the client
might have to start the conversation from scratch.
Hang on, now I see that your example says _dkim.mx01.example,
is it the server using an underscore, in MX records ? Or in
the greeting ? It's not that I'm against any "updates: 2821",
but I'd like to know if it's the direction you talk about.
Frank
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