[exim] smarthost Outsmarting me so Far

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Autor: martin.m
Data:  
A: exim-users
Assumpte: [exim] smarthost Outsmarting me so Far
for some reason, I had it in my head that the verbose form of
send did not report much. It reports a lot with the -snoop and
-watch flags set so here is what is always happening these days
as seen by exim, itself and nmh. Some of us still use it;-)

I send a message and here's the log with comments.

LOG: MAIN
Warning: No server certificate defined; will use a selfsigned one.
Suggested action: either install a certificate or change tls_advertise_hosts option

#I did generate a cert and it is in /etc/exim4 and I still get
this warning, but one thing at a time.

LOG: address_rewrite MAIN
"martin@localhost" from env-from rewritten as "martin.m@???" by rule 1

#so far, so good.

LOG: MAIN
<= martin.m@??? U=martin P=local S=487 M8S=0 RT=0.009s
LOG: MAIN

delivering 1nolOX-0005He-Bd
R: smarthost for martin@???
T: remote_smtp_smarthost for martin@???
Transport port=25 replaced by host-specific port=587

#Again, good.

Connecting to smtp.mx-altice.prod.cloud.synchronoss.net [208.180.40.68]:587 ... connected
SMTP<< 220 omta02.suddenlink.net ESMTP server (InterMail vM.8.04.03.22.02 201-2389-100-169-20190213) ready Wed, 11 May 2022 07:24:45 -0500
SMTP>> EHLO wb5agz

  SMTP<< 250-omta02.suddenlink.net
         250-HELP
         250-XREMOTEQUEUE
         250-ETRN
         250-AUTH=LOGIN PLAIN
         250-AUTH LOGIN PLAIN
         250-PIPELINING
         250-DSN
         250-8BITMIME
         250-SIZE 52428800
         250 STARTTLS


#hinse forth, this will be #Banner.

SMTP>> STARTTLS

SMTP<< 220 Ready to start TLS

#This looks right so far but What could possibly go wrong?

SMTP>> EHLO wb5agz


#Banner once again but the script marches on

SMTP>> MAIL FROM:<martin.m@???> SIZE=1524


I think we just saw what goes wrong. There probably should have
been an "auth login" response sent followed by the authentication
sequence but no such luck.

SMTP<< 553 Authentication is required to send mail as <martin.m@???>

#exim doesn't realise that this isn't what should be sent and is
proceeding as if all is well.


SMTP<< 503 Bad sequence of commands (specify MAIL first)
SMTP<< 503 No sender specified
SMTP>> QUIT


    So, the question is, Does this look like I can rearrange
things somewhere to correct what is happening?


    In the slightly less opaque world of text-based expect
scripts and thelike, one just makes sure not to get ahead of the
responses from the remote site so as to send the appropriate response
or envoke a case or switch module.  In this case, we seem to be
totally missing what SMTP is asking for next.


    When trying to read the network traffic, all that key
changing and restarting was the remains of the broken mail
transfer sequence and smtp.suddenlink's server dropping the
connection several times.


    When Suddenlink.net upgraded something around March 14,
the banner changed and the server doesn't appear to use Port 465
in any way.  I've fixed that situation in that I call for 587 in
/etc/exim4/localmacros by editing the appropriate line as shown:


MAIN_TLS_ENABLE = 1
REMOTE_SMTP_SMARTHOST_HOSTS_REQUIRE_TLS = *
TLS_ON_CONNECT_PORTS = 587
REQUIRE_PROTOCOL = smtps

    Putting localmacros in or taking it out has no effect
and, of course, I am running dpkg-reconfigure exim4-config each
time after the change.


    I must admit that I strangely feel a bit satisfied that
one can actually see the place where things go wrong.  It's just
as important  to know what doesn't need tweaking as what does.


Again thanks for any and all constructive ideas.

Martin McCormick