Re: [Nmh-workers] mts.conf has me Baffled.

[Ken Hornstein]

>I'm not sure  what ``most MUAs'' represents, but perhaps  this refers to
>Outlook and Thunderbird (and other ``popular'' UI oriented MUAs)? If so,
>don't most  of these MUAs  have an ``outbox''  which is actually  just a
>local  mail queue  built  into the  MUA which  retries  delivery to  the
>configured SMTP server?

Well, I was speaking about MUAs that run on Unix systems, which would
include Thunderbird but exclude Outlook.  But that's a fair question ...
what does 'most' mean?  Number of users?  Or just each MUA count as '1'?
I think in the back of my mind it was based on number of users, but I don't
suppose that is really definite.

And for if those MUAs have queues ... well, in my experience it depends.
The more "full featured" GUI ones like Thunderbird usually do, but not
all of them.  So I would say "queue support" is not universal.

>Does nmh have a queue?

Well, if you have a draft folder, you could consider that a poor man's
queue (it would be easy to write a script to send everything in your
draft folder).

>I've long thought that  /usr/sbin/sendmail (or /usr/lib/sendmail on some
>systems) was widely used by most CLI oriented MUAs (mutt, mailx, etc...)
>precisely because  they didn't have their  own queue. I could  be wrong.
>:-)

Well, let's break it down then.  Here's a list of all Unix-based MUAs
I was able to find.  I tried to keep it to open-source ones that are
actually maintained (sorry if you're an Elm user).  I included graphical
as well as command-line ones (sometimes the line is not so clear, in
the case of things like Gnus), but I excluded things that are just nmh
front-ends like exmh and MH-E.  Additions to this list are welcome.  In
my experience the closed-source MUAs only support SMTP submission, but
I'd be welcome to be proven wrong.

- Thunderbird

  As far as I can tell, the only option for Thunderbird is to configure
  the SMTP server directly.

- Claws Mail

  Again, it seems like the only option is to configure an SMTP server
  for direct submission.

- Evolution (Camel)

  It look like you can configure submission either via a sendmail binary
  or directly via SMTP.

- KMail

  The documentation is a bit sparse, but it looks like it only supports
  direct SMTP submission.

- mutt

  Mutt can do either SMTP or call a sendmail binary.  This is a relatively
  recent feature; I know that for a long time the Mutt developers resisted
  adding SMTP message submission support.

- Alpine

  It might be stretching it a bit to call Aline supported (last release
  in 2008), but it can do either SMTP or call a sendmail binary.
  Interestingly enough, it wants to do the same thing that nmh does
  (speak SMTP to a local sendmail process).

- Gnus

  Gnus can do either SMTP or sendmail message submission; it seems the
  default depends on settings in the Messages library.

- Balsa

  Can do SMTP or sendmail submission.

- mailx

  The original, stock, OS-supplied mailx cannot do SMTP submission AFAIK.
  But the open source alternative, Heirloom mailx, can (it also supports
  IMAP).  From the Heirloom mailx web page:

  Supports SMTP to send messages directly to a remote server. A local
  sendmail interface setup is thus not necessary. In combination with
  OpenSSL or NSS, both the STARTTLS method and SMTPS can be used. SMTP
  AUTH is also supported.

So if you look at the list I compiled, every modern open-source MUA I
found supports SMTP message submission.  A majority (6 out of 9) support
submitting messages to a sendmail binary (it's not clear if they are the
"sendmail -t" type, or expect sendmail to talk SMTP).  So, a lot more
MUAs support sendmail submission than I expected, even a number of the
graphical ones; I was clearly wrong to say otherwise.

But ... it's clear to me that not all of those MUAs support queueing.
For example, I'm pretty sure mailx and mutt do not, and probably alpine
as well.  I can't speak for the graphical ones.  It's probably easier
for those since you pretty much have to be able to handle events and/or
threading to support a full GUI.

>If the  goal is  to make  nmh behave  more like  popular MUAs,  and work
>independently of a properly configured MTA then, shouldn't nmh also have
>a queue?

Well, it's not clear if they all do.  It's hard to have a independent
queue in the MH command model, since MH/nmh aren't monolithic; how would
you do that?  But like I said, if you have a draft folder doing a queue
would actually be very simple.  Just create message drafts as usual and
use something like this to send them (untested):

#!/bin/sh

DRAFTS=$(MHCONTEXT=/dev/null scan +drafts 2>/dev/null)

if [ "$DRAFTS" ]; then
        for message in $DRAFTS
        do
                send -draftfolder +drafts $message
        done
fi

Or something close to that.

Speaking to my larger point ... it's obvious to me that since every modern
MUA I could find supports direct SMTP submission, that's still a useful
feature to keep around.

--Ken