On Fri, 15 Mar 2002, John W Baxter wrote:
> A note: Exim 3.32, if the remote host ignores the 501 error and presses on
> with the message after sending an invalid EHLO, delivers the message with
> no special notations I can find in mainlog. None are associated with the
> message ID, anyhow. Do the RFCs require/allow this behavior?
Not strictly, according to 2821:
"In any event, a client MUST issue HELO or EHLO before starting a mail
transaction."
You can request this behaviour in Exim by setting helo_verify_hosts = *
but that does also do additional checking, which you may not want.
In Exim 4, you could achieve much the same effect by putting this test
in the ACL that is obeyed at RCPT time:
deny message = "EHLO needed"
condition = ${if eq{$sender_helo_name}{}{yes}{no}}
which effectively tests that a HELO/EHLO name has been supplied.
When I first implemented Exim, I think I copied its behaviour from
Smail. In those days, one wasn't particularly bothered by determined bad
guys, and the presence or absence of EHLO didn't seem particularly
important.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
