One of the questions was about the "The client SHOULD send an EHLO
command as the first command after a successful TLS negotiation." As
with everything SMTP, there are two sides, the sender and the receiver.
Instead of thinking in terms of whether the sender should send the
command, we could look at this in terms of whether the receiver must
accept a mail transaction without being sent an EHLO command. I don't
see anything in the specifications that say that.
The more I think about this, I think its just all fine. We had one
client presented here who failed to reissue a EHLO/HELO as expected in
practice. The server issues a negative response and the client failed
to continue properly. Even if the implementer read 3207 as a SHOULD,
that alone should be enough to tell the client that it MAY have to
reissue the EHLO/HELO if the MAIL FROM: command failed.
In other words,
SHOULD says "Be Prepared To Reissue EHLO/HELO"
There is nothing that says that it does not need to send it and abort
the transaction if the server requires it.
Hector Santos, CTO