Path: utzoo!attcan!uunet!ogicse!ucsd!sdd.hp.com!think!barmar
From: barmar@think.com (Barry Margolin)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Dial up access to Internet facilities
Message-ID: <36901@think.Think.COM>
Date: 29 May 90 22:12:16 GMT
References: <1990May25.163528.14300@ameristar> <9005270423.AA19852@psi.com> <1990May29.191125.9800@portia.Stanford.EDU>
Sender: news@Think.COM
Reply-To: barmar@nugodot.think.com (Barry Margolin)
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 31

In article <1990May29.191125.9800@portia.Stanford.EDU> morgan@jessica.stanford.edu (RL "Bob" Morgan) writes:
>Indeed, SMTP's assumption that everybody's connected all the time
>doesn't work well with occasionally-connected hosts.  It would seem
>that the time is ripe for some sort of extension to SMTP to do
>receiver-initiated transfers to meet this need.

No extension is needed: see the TURN command.  However, most SMTP
implementation don't enable this command for security reasons.  To make it
secure you need a way of authenticating the calling SMTP.  One possibility
would be to allow it only in cases where the name given in the HELO command
corresponds to the address being used by the transport layer; however, not
all transport layers make this available (what do you do if SMTP is being
done over dialup lines?).

>Note that POP doesn't make it for the small-business customer.  I want
>my address to be "morgan@mybusiness.com" not "morgan@barrnet.net".  I
>also want to manage my own accounts on my own multi-user system, not
>ask my provider every time I need a new one.

MX records solve the first problem.

However, I'm not sure why you need any of this.  What's wrong with the
MX'ing host periodically trying to connect to the occasionally-connected
hosts?  Much of the time it will just time out, but when it succeeds it can
forward all the accumulated mail.  This is the default behavior, so no
extensions are necessary.
--
Barry Margolin, Thinking Machines Corp.

barmar@think.com
{uunet,harvard}!think!barmar