tobold.org

correct • elegant • free

△ uk.net △

◅ POP3/SMTP - Whats the difference?

RFD: Renaming uk.wic to uk.org.women-in-comp ▻

POP3/SMTP - Whats the difference?

In article <19950623.175015.07@tquest.demon.co.uk>,
Joshua Goodall <josh@tquest.demon.co.uk> wrote:
>I've just had a rummage through RFC1460 and got the impression
>that POP3 is a one-way protocol, relying on SMTP to send outgoing mail!

Correct, as I mentioned in <3s3qon$4u7@pipe.pipex.net>.

>So why bother implementing both protocols on a mail server? If someone
>could be arsed to implemented SMTP with TURN (for a change) then
>you could be sure that your mail would come down the line when you
>wanted it to.

There is a "chicken and egg" aspect to this.  Obviously the client and
server must agree on how mail will be transferred.  There is no demand
for servers which implement TURN, because there are no clients which can
use it.  And vice versa.

This situation arose initially probably because there are some security
issues with TURN.  It is, I believe, possible to surmount the problems
(at the expense of limiting the circumstances under which TURN can be
used, and ignoring several layering abstractions), but I'm not aware of
any implementations.

There is an Internet-draft, draft-myers-smtp-auth-01, which describes an
authentication mechanism for ESMTP transactions.  Obviously this solves
the security problem, but I suspect that inertia and the "chicken and
egg" cycle will mean that TURN is never widely implemented or used.

Tim.
--
Tim Goodwin        | "If you're used to paint-by-number, a blank canvas
Public IP Exchange | can be unsettling at first." -- Larry Wall

Original headers:

From: tim@pipex.net (Tim Goodwin)
Newsgroups: uk.net
Subject: Re: POP3/SMTP - Whats the difference?
Date: 26 Jun 1995 13:20:08 +0100
Organization: PIPEX, 216 Science Park, Cambridge, England
Message-ID: <3sm8lo$f5f@pipe.pipex.net>
References: <3s6cd5$ckm@xl5.geac.co.uk> <3s9a7n$rrn@imp.demon.co.uk>
  <3s9s3n$1o5@altos.idiscover.co.uk>
  <19950623.175015.07@tquest.demon.co.uk>

△ uk.net △

◅ POP3/SMTP - Whats the difference?

RFD: Renaming uk.wic to uk.org.women-in-comp ▻