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Re: Keep Alive Response Codes [Re: slow email validation problems (was reject vs bounce)]

2005-09-16 22:48:05


----- Original Message -----
From: "John C Klensin" <john+smtp(_at_)jck(_dot_)com>
To: "Hector Santos" <hsantos(_at_)santronics(_dot_)com>; "Harald Tveit 
Alvestrand"

...
All MUAs, including Outlook, have a MTA (SMTP client)
component.  How else will it send mail to a SMTP server or
host?

Fascinating.   Having been involved in writing an MUA or two
that did no such thing, and seen several others, I'm really
happy to hear about the "All" part.    The two other models I'm
aware of are:

* the MUA uses some sort of API function or private
protocol to get the message content and headers (only)
to the MTA and the MTA constructs the envelope.  This is
the classic story that motivates submission servers, but
submission servers whose "incoming" side is not SMTP.

* the MUA uses a different sort of API function or
private protocol to queue or send out a complete
message, with enough information capacity in those
functions to specify the behavior of the SMTP server,
including the envelope, queuing times/ behavior, etc.

Sigh
   john

I am perplexed by your question or questioning of what I believe was a well
understood generalize concept about a MUA.  But maybe that was my mistake.

What kind of MUA are you talking about?

I've design, authored, documented, managed, marketed and supported atleast
6-7 Mail User Agents or Applications.

Are we talking Dump Terminals? VT100s? Direct Online systems?  Thin Clients?
Fat Clients (PCS)?

I will try to take the high road here and try to bring it back to 2821.  I
think the issue is more how we want to illustrate topologies or paths:

     MUA ---> MSA  ----> MDA ----> MUA

Whether its integrated or built-in or separate, dynamic, event driven or
scheduled, this generalization implies a transfer component is part of the
MUA.

Is the more technical correct illustration?

    MUA ---> GATEWAY --> MSA/MTA ----> MDA ---> GATEWAY ---> MUA

How do you want to show it?

Today, we can probably break up the MUA into parts:

    - MAIL READER
    - MAIL WRITER
    - MAIL MANAGER
    - MAIL TRANSFER AGENT

What parts it has depends on the MUA type you are referring to.  Are you
thinking x822/x821 only?

Any way you put it, there is always a "transfer component" in a MUA,
integrated, built-in, API, other whatever.

I hope we are not going to nitpick about this?

--
Hector Santos, Santronics Software, Inc.
http://www.santronics.com

PS: Product designs exclusive with MUA components

Early 80s:

 - EMAILATATOR, TAPCIS like System for Westinghouse
   Early Screen Dumping Text Capturing Technology.

 - OPUS XPRESS (OX) - World first Fidonet Offline MUA, 3rd overall.
   Worked with Intelligent Backend Engine Installed on Hosting System.

 - SILVER XPRESS (SX) - New OX for 22 mail systems. MUA with NO MTA
   Santronics started to enter into new cottage industry of Cyberspace
   and Telecommunications Markets. Voted by PC Magazine 3rd most
   pirated shareware product after QEDIT and PKZIP!

Late 80s/Early 90s:

 - GOLD XPRESS (GX) - new SX with GUI and MTA, Demostrated at ONE BBS CON
   trade shows.  The beginning of RIP, MINETEL like systems, i.e. Prodigy,
   etc, before HTML stated to take hold.

 - PLATINUM XPRESS (PX) - 2nd Integrated MUA, FRONTEND, MAIL/FILE GATEWAY

1996:

 - TITIUAM XPRESS (TX) - To complete picture - A new online hosting system
   never released. Instead we acquired Wildcat! - the World #1 Online
   Hosting System.

1998 - until present

 - WILDCAT! - Supports Online MUA, Offline MUA, Mixed MUA - mixed
              multi-device system.

 - WIldcat! Navigator - GUI FILE, MAIL, CHAT, IM, GAMING Frontend

2005 and beyond

 - SMARTER MUA and BACKENDS! More secured client/server handshasking,
   Email Security, P2P, etc,  Need advancement in 2822 and 2821. New
   pressures to invent new formats.


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