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Re: BSMTP on debian.net

On Fri, Feb 16, 2001 at 12:06:16AM -0700, Jason Gunthorpe wrote:
> As suggested, I have setup BSMTP in a rather neato way I think. Well,
> mostly, it is still kind of experimental. :>
> The first group of people I am aiming this at are people with relatively
> stable connectivity, such as a DSL or cable modem user. These people will
> be able to run a SMTP server and reasonably expect their IP to stay
> constant for months at least.
> These folks will register a debian.net entry, pointing to their
> quasi-static IP with a mx 0 pointing to their entry and a mx 10 to
> klecker. When their IP changes (since it is only quasi static) mail will
> spool quietly on klecker until the DNS IP is changed, then it will spool
> back out to the SMTP server. [1]

this sounds like a useful and worthwhile thing to do, but why use smtp
rather than uucp?

smtp isn't terribly reliable for delivery to dynamic IP addresses - as
you know, since from the description you posted you've put in a fair
amount of effort trying to work around the problems. much of that effort
duplicates what is already available with uucp.

it's quite easy to setup uucp over tcp feeds for email, and it's also
easy to use stunnel as a wrapper for uucico so that the entire session
is encrypted.

one big advantage of uucp is that absolutely nothing at all is dependant
on the client site's IP address - doesn't matter if it changes every
hour or every 6 months. mail just gets queued for them until they poll
to pick it up (a cron job runs to auto-bounce mail that's stayed in the
queue for too long...configurable) from wherever they are. no need to
change MX records or do anything else.

it can also be set up so that the client sends their outbound mail via
uucp too, thus avoiding the hassle of setting up pop-before-smtp or
other auth kludge for smtp.

uucp-over-tcp is great if you're travelling too, as long as you can
get your debian laptop onto the internet somehow (at a net cafe or
university or whatever) you can poll to pick up your mail.

if you're interested in finding out more about this, feel free to
ask....i've set this up for several sites now (including one friend
who moved from .au to .uk. he's on a NATted & firewalled private
address-space cable internet provider in the UK - he polls my server in
australia regularly with no problems)

you can see an extremely brief mini-HOWTO on setting up uucp with
stunnel & openssl at http://taz.net.au/postfix/uucp. one of these days
i should rewrite it so that it doesn't assume you already know uucp and
only need instructions for the ssl stuff.

> Oh, if you screw it up and start sending your cron mails to
> root@debian.org, I will box you up and send you Branden so he may have
> his way with you.

a dire threat. branden is the evil genius behind the Sodomotron 2000<tm>
and is probably working on the 2001 model as we speak.

> Note 1 - Of course if your IP changes often there is a chance that the
> new owner might also be running a mail server and might just trash all
> your mail, kind of sucks, but hey..

this is one of the major reasons why smtp delivery to non-static IP
addresses really really sucks. it's non-solvable - i.e. the problem is
inherent, even with the best dynamic dns system in the world there is
always going to be a small window of opportunity for your mail to be
misdelivered...you either put up with less than 100% reliability or you
look for another solution (and that solution, surprisingly enough, is


PS: sorry, but uucp is one of my bugbears...or at least, the fact that
people ignore it's existence and then reinvent it using ugly POP and
SMTP hacks. hmmm..."those who don't know uucp are doomed to reinvent
it poorly" :). the point is that one of the tasks uucp was *designed*
to do was provide reliable mail service for hosts without a static IP
address (or even without any kind of IP connectivity). it does that job
extremely well, and has a particularly valuable and useful niche these
days with uucp-over-tcp and encrypted uucp-over-tcp using stunnel &

craig sanders <cas@taz.net.au>

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