Exim configuration for dialup users (was Re: Exim as default mailer)
On Wed, Nov 11, 1998 at 11:38:16AM +0100, Paul Slootman wrote:
> In article <[🔎] c=UK%a=_%p=Origin-it%l=UKRUX002-981110102235Z-8111@ukrax001.ras.uk.origin-it.com> you write:
>
> >As I have a single-user home PC with dial-up access to my ISP, I fall
> >squarely into the category of users for whom Exim is "not particularly
> >well-suited". Is this a real problem, or is Exim a good mailer for
> >dial-up systems?
>
> I've created two exim.conf files, one for use when I'm online, and
> one for when I'm offline. I switch these around via
> /etc/ppp/ip-*.d/exim:
> I have "queue_remote" in my exim.conf.autodial which means it doesn't
> attempt to deliver these directly. Just either don't run the cron job
> that flushes the queue periodically if you don't want connections to
> happen solely for email delivery (or if you don't have dial-on-demand!).
Exim works fine for home users, but there are five areas that are
tricky to configure:
** "local_domans" should have ALL the names your local network is
known by; e.g., "local_domains = townhouse:localhost".
** don't use the "visible_name" stuff or you'll find that messages to
people at your ISP get delivered locally.
** I have all the queue options commended out (queue_smtp, queue_remote,
queue_only, queue_run_in_order). Mail delivers immediately, but if
it can't (e.g., network is down) it just gets queued, no problem.
I run the queue manually when I want to, but you could also do it
within ip-up or via cron. If you have dial-on-demand and don't want
the link going up for email, edit the diald config file to ignore
SMTP (and you'd also need to specify your smarthost via IP#, so
it doesn't cause a DNS lookup, which would activate diald).
** You'll need to use your ISP's smarthost, because some sites will
reject your mail if you try to deliver it directly, because your
local domain name (that exim knows about) is different from the
name associated with the (dynamic) IP you're currently connected on,
so exim gets the HELO argument wrong and I don't know how to fix it.
# In the ROUTERS section of /etc/exim.conf
smarthost:
driver = domainlist
transport = remote_smtp
route_list = "* smtp.my_isp.com bydns_a"
end
** Rewriting the From: address takes forever to get right. I'm
currently using:
*@*.local_network isp_name@isp.com Ff
If this is absent, you'll end up being From: local_name@local_domain,
which is not accessible from Internet. Other misconfigrations
cause local_name@isp.com (somebody else, or a nonexistent user)
or root@isp.com (which your ISP will be real happy about). However,
at least it's easier to get this right under Exim than any other MTA.
** It's difficult to funnel multiple local users through one ISP pop
account. I've never gotten this to work. Some people use the
comment part of the to-address to determine who it's going to.
Others use the "-suffix" method, where mail to
you-suffix@your_isp.com goes through your .forward filter based on
"-suffix". But I think that requires Qmail and cooperation from your
ISP.
As another person stated, the problem is really SMTP's fault --- it's
inadequate for dialup users with dynamic IPs. But UUCP is frequently
not an option because most ISPs don't know what it is and those that do
charge extra for it.
I've sometimes thought, wouldn't it be better to use Qpopper's upload
feature? That way, the authentication depends on knowing your username/
password, which is much more reliable than the domainname/ reverse
domainname checks SMTP does. It would be easy enough to write an
Exim transport which contacts the remote popserver. Unfortunately, it
means the ISP would have to change to Qpopper, and they'd probably say,
"But our current system works fine for our Windows users. And we don't
support Linux anyway."
--
-Mike Orr, mso@jimpick.com
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