Re: Gnus with Exim

["Steven E. Harris" <seh@panix.com>]

David Abrahams <dave@boost-consulting.com> writes:

> It's working!  This is fantastic, thank you!

Great news.

> A few more questions
>
> 1. I allowed exim-config to start it as a service:

[...]

>    I figured that's what I needed to do in order to get the
>    asynchronous sending behavior I'm after (remember that my SMTP
>    server is not responsive enough for me).  Is that right, or is
>    there a way to do this that only causes exim to run
>    (asynchronously) when it's time to actually send something?

I assume you mean that no service runs until it's time to send a
message? Exim will work fine that way, but the problem comes right
back around to your raison d'etre for setting up exim in the first
place: When a sending attempt fails, the message will be queued, but
there will be no automatic retrying and dispatching of that
queue.

That is, you are free to call on exim at any time to send an outbound
message, but if that first attempt fails you may be on your own for
triggering exim to try again later. Some experimentation may reveal
that the /next/ time exim tries to send another message, it will also
process any other pending messages in the queue. I'm not sure about
that.

One thing that does seem helpful, observable through casual
experimentation, is that even when exim is invoked to accept an
outbound message with no daemon running, it accepts and sends the
message with two different processes, so the calling program doesn't
block through the sending attempt.

> 2. Of course, my ISP not only insists that I use their SMTP server
>    when I'm at home, but their server refuses to respond when I'm
>    away.  So I have to use smtp.boost-consulting.com.  I don't want to
>    edit my exim-config and restart the daemon in those cases if
>    possible.  Any ideas?

I used to have this problem, and my solution was barely mentionable: I
had a script that flipped the permissions on exim.conf, swapped a
symlink to one of three nearly-identical configuration files, and
restored the permissions. I could have ran sed or similar over the
file to swap the server names, but I didn't like seeing the
modification times change on the file(s).

Debian has a system wherein the actual exim.conf file is generated
from a separate set of settings and small template files. With that
arrangement, it would be possible to change the server setting and
regenerate the file. Again, though, that's a hack.

Exim does have all sorts of read-and-search-this-file-or-database
capabilities. Debian uses it for the /etc/email-addresses lookup, and
also to plug in the user name and password for SMTP AUTH/TLS, instead
of the in-line specification I showed you. Perhaps we could figure out
how to get exim to read the smart host server from a separate file,
and you could just change that separate file when your computer
roams. If you're interested in pursuing this idea, I can help with the
research.

When I mentioned that I "used to" have this problem, I only "solved"
it by discovering that my ISP (Panix) runs its SMTP server on several
alternate ports. That allows me to use the Panix server at home with
my cable modem despite SMTP being blocked, and to use it when out in a
cafe or library because again the alternate SMTP port isn't usually
blocked.

> 3. My IMAP server is not super fast either.  It's running Exim too,
>    coincidentally.  Ideally I'd like to set up a mirror of my IMAP
>    server on a local Linux machine so I can search messages more
>    quickly and have redundant message storage.  Do you happen to know
>    of a means to that end?  I imagine this isn't something people want
>    to do every day.

I have never attempted this, but I'd imagine it would involve having
something like fetchmail poll your ISP's mail server, download local
copies of the messages to the IMAP server, while leaving the messages
on the ISP's server. However, that would not handle the problem of
synchronizing message deletion, copies, moves, and flag
alteration. Suddenly the problem gets much harder.

> Thanks again for all your help.

No problem. I've been a casual exim tinkerer for a while now, and
always enjoy the chance (or the excuse) to learn a little more about
it.

-- 
Steven E. Harris