submission vs smtp

Michael Richardson <[email protected]> Thu, 05 Jun 2025 11:49:46 -0400

Newsgroups	gmane.mail.nmh.devel
Message-ID	<[email protected]>

On Sunday I dd'ed a finnix iso overtop of my desktop HD rather than USB key.
(Cause my mortal user was in the "disk" group). After restoring from
backups, I found that my NMH config wasn't quite right. I didn't recompile
it, because it was on my "/sandel/bin" partition, which was just restored
intact, yet...

It was trying to use the submission port (465) in Post. (and failing)
My desktop (and laptop) configuration is sufficiently ancient that I thought
I was using either sendmail -bs, or localhost:25. I don't think that I had
submissions port open. (My desktop and laptop do authentication, client TLS,
relaying to smarthost). I go back to days when one edited sendmail.cf
manually, (not even m4 macros...)

I read through mts.conf man page and even into mts/smtp/smtp.c, and I
honestly can't really figure if/when it picks submission over port-25.
I'm guessing that something changed as the default.
Maybe we just don't support port-25 at all, because it's not 1999 anymore.
Maybe I'm wrong that I wasn't using it before.

It's not, in the end, a big deal, but I did wonder about it, and I think that
maybe the mts.conf (mh-tailor) should say more. Presently it says:

A single hostname to be used when performing mail **submission** via SMTP. Previous
It is not possi‐
ble to change the mail submission port number in the servers entry; see the -port
switch to send(1) for this functionality.

and I think this is the only mention that it's doing submission rather than
SMTP. I think that it should probably say more. Not sure exactly what.
Probably something at the top, and under SMTP support, and also on the send
and post man pages.

I don't think we suport TLS client authentication at all for submissions.
I presently run postfix on localhost, and then I smarthost via authenticated
SMTP on port 26. Because port-25 would be blocked. Perhaps I ought move to
sending to my smarthost via submissions port, but I'd want to use TLS client
authentication/authorization.

signature.asc (application/pgp-signature, 511 B)