Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!cca!mirror!adelie!minya!jc
From: jc@minya.UUCP (John Chambers)
Newsgroups: comp.mail.misc
Subject: Re: routing in the user agent
Message-ID: <287@minya.UUCP>
Date: Wed, 14-Oct-87 21:57:02 EDT
Article-I.D.: minya.287
Posted: Wed Oct 14 21:57:02 1987
Date-Received: Sat, 17-Oct-87 04:18:09 EDT
References: <279@minya.UUCP> <7461@g.ms.uky.edu>
Organization: home
Lines: 44
Keywords: bounced mail, rerouting

In article <7461@g.ms.uky.edu>, david@ms.uky.edu (David Herron -- Resident E-mail Hack) writes:
> In article <279@minya.UUCP> jc@minya.UUCP (jc) writes:
> 	[ Deleted quotation from someone describing their personal
> 	  algorithm for sending mail ... i.e. Look at the address
> 	  and determine where the site is, and re-write the address
> 	  appropriately.  All by hand. ]
> [ Deleted rephrasing of Prolog resolution applied to mail paths]
>
> hmmm ... how are you intending to test the path?

Easy send it; if it bounces, that's a failure to resolve that path.
 
> You don't have the needed information on your machine.  NOBODY does.
> The only information you have is the UUCP Project database, and that's
> gauranteed to be at least 1 to 2 months out of date.

Nonsense.  I have much better info than that.  My mailer extracts the
paths from all incoming mail and puts it (with a timestamp) into the
database.  I thus have good info on good paths to those people who
have sent me mail lately.  This is at worst the same data as is used
by the mailers; it is usually better.

> Obviously it's a good algorithm but I don't see the point of making
> it "automatic" like you suggest.

Only because I get tired of doing something by hand when it could be
done better by a computer.  That's why we buy the little beasts, after 
all.

Anyhow, characterizing the Prolog algorithm as "try it again until it
works" is a bit inaccurate.  Hunting around at random is quite a bit
different from a systematic search through a list sorted according to
recent successes.

The current proposals for intelligent forwarders strike me as being
basically an uncoordinated random walk.  This will work, most of the
time, and the mathematics of it all is over a century old.  But there 
are much better algorithms known.  The Prolog approach has the distinct
advantage of being implementable on the originating machine.  But it
does require that the sender be able to dictate the path, and that
other mailers not try to "improve" it.

-- 
John Chambers <{adelie,ima,maynard,mit-eddie}!minya!{jc,root}> (617/484-6393)