Re: [Exim] Exim on a single-user system

Matthew Byng-Maddick wrote:

> On Mon, Dec 31, 2001 at 05:50:22PM -0500, Derek Broughton wrote:
>
>> > Here's the problem. A MUA should not be dealing with SMTP -- an MTA
>> > should. mutt (and, AFAIK, elm and pine) do not do SMTP at all.
>> > Instead they pipe the message to the system's MTA and let it take
>> > responsibility for delivering it.
>>That hair needs an electron microscope to split. :-)
>>
>
> Not at all. There is a huge difference. Do you, for example, always have
> an X/Window display available. The reasoning is very similar.


I fail to follow. NO I don't always have a X Window display. YES I
always have an SMTP port available - if not on this machine always on my
ISP.


>>I can't imagine any good reason why an MUA shouldn't deal with SMTP. In
>
> How many MUAs do you know which are able to spool messages if the
> receiver SMTP doesn't want to accept them just yet?


In which case, every one of them asks you what to do with it and usually
saves it in some 'drafts' folder. That's not ideal from one point of
view, but certainly is from someone who wants to be able to use the same
software on multiple machines which won't all support piping to an MTA.


>>fact, as configured, SMTP on localhost is usually your MTA. It makes
>
> No it's not.


Of course it is. If you have SMTP on localhost, are you trying to tell
me it WON'T be your MTA? You're running an MTA and a separate SMTP
server? Isn't that rather redundant?

> Please read up on /usr/{lib,sbin}/sendmail -bs which should
> be the canonical submission form for an MUA.


Says WHO? Please point me to the RFC for that. That is A valid
submission form. In fact that's exactly what my SMTP process is running
(well, exim -bs really).


>>much more sense for every MUA to assume it has access to an SMTP port on
>>_some_ host than to assume that it will have access to an MTA program.
>
> Huh? have you never had a network outage?


Of course, but on my system you can deliver to SMTP on localhost (hey,
I've never lost _that_ one on a network outage) or to an available SMTP
host anywhere else on the network.

> The reason that one should use the program and deliver stuff via a pipe
> on the local machine is that SMTP requires ability to cope with network
> outages and the transfer of responsibility. These are both complicated
> to deal with, because you need to have a spool of messages, thus it is
> the MTA's job.


But that's totally unchanged by having the MUA deliver the mail to SMTP
on your localhost. In fact, it's quite simple to set exim up to only
permit SMTP connections from it's own host, so it should be as secure as
the pipe.


> Leave the job of queuing and accepting responsibility to the system which
> can deal with it.

Every mailer I've used _does_ that - even the infamous Microsoft Outlook
Express. It does however refuse to hand it off if the receiving SMTP
host refuses to accept responsibility.

derek