mutt courier exim4 - configuration help required

["Richard Lyons" <richard@the-place.net>]

I am really beginning to hate squirrelmail.  It doesn't thread, it
doesn't break lines to 72 (or whatever) chars...  But I am stuck
with using it unless someone can tell me where to look for my
misconfiguration.  I have a server (actually a vm with Bytemark) on
which I run courier-imap and exim4.  Then I can log on from anywhere
and read my mail using mutt on the laptop.  When I want to reply, I
have to open the same mailbox in squirrelmail and reply from there.

There are two issues AFAICS. I could send by sshing onto the server
and running mutt there, or I can configure something so that the
mutt on the laptop can send mail. Running on the server is less
convenient obviously.

1 - mutt on the server.  Mutt runs, but access over a slowish
    connection (GPRS) seems halting and in any case mail delivery fails.
    Mutt thinks it has gone, but each attempt to send has a set of
    messages in /var/log/exim4/mainlog similar to this:

2007-05-05 13:35:42 1HkJUE-000170-0o ** --@the-place.net: Unrouteable address
2007-05-05 13:35:42 1HkJUE-000170-0o ** hdrs@the-place.net: Unrouteable
address
2007-05-05 13:35:42 1HkJUE-000170-0o ** -r@the-place.net
<-R@the-place.net>: Unrouteable address
2007-05-05 13:35:42 1HkJUE-000170-0o ** delay@the-place.net: Unrouteable
address
2007-05-05 13:35:42 1HkJUE-000170-0o ** failure@the-place.net: Unrouteable
address
2007-05-05 13:35:42 1HkJUE-000170-0o *> someone@domain.tld R=smarthost
T=remote_smtp_smartho
st H=smtp.bytemark.co.uk [80.68.81.166]

    after which it is never heard of again (i.e. never arrives).

    I don't have the first idea where to look for this problem.  I found
    nothing useful with google.

2 - mutt on the laptop.  If I want to send mail from mutt on
    the laptop, I can either use the ISP's smarthost (which means a
    different configuration depending where I am accessing the net) or
    send via the imap server which sends by the smarthost of
    Bytemark (which is presumably what squirrelmail does).

    But my mailserver of course rejects what it sees as relays (I
    guess this is debian default configuration, and I obviously do
    not want to allow relays).  So I assume I need to set up some
    kind of authenticated remote logon.  I have four times tried to
    follow the guide to configuring Exim4 and Courier IMAP under
    Debian at
    http://trekweb.com/~jasonb/articles/exim4_courier/index.html
    but am always snagged by the chapter on TLS which seems to
    set up okay, but near the end when the authentication goes
    "live" causes an error
    "*** No acceptable authentication types available"
    As there is no indication what might be the problem, and again
    google produced no useful help, I have had to unpick the work
    and abandon the exercise.

So, can anyone who uderstands mail explain to me where to look for help
on any of the above, or where else to find a guide to configuration
that would allow me secure remote access to the imap using mutt?

Sorry this is so long.

TIA

--
richard