RE: Email messages: How large is too large?

[Vernon Schryver <vjs at calcite.rhyolite.com>]

> From: "Linscheid, Sven" <Sven.Linscheid at dresdner-bank.com>

> Sorry, girls and boys. I could not understand what this
> discussion should keep here.
>
> You're discussion a point which everyone should decide 
> in there own world.
>
> I think Mails from 1 k - 1000 MB are OK. Because with
> a 10GB Connection is that really something like should
> I drive a Porsche or an Lamborgini!
>
> This is not the place to discuss such a stuff!
>
> Use a newsgroup for it, that like nonsene.internet.org!

That statement is as wrong as the statements that there should be no limits
on SMTP message sizes.  The main charter or goal of the IETF is about
interoperability.  What started this thread was a reference to the ancient
complaint about very large SMTP messages not getting through.  It as a
reference to an interoperability problem among SMTP servers, and as such
is clearly an IETF topic, although perhaps not for the main list.
The maximum size of SMTP messges is just as legitimate a topic today
as it was when section 5.3.8 of RFC 1123 was published 10 years ago.

Without a published standard for a maximum SMTP message size, users are
unable to know when their email messages will be delivered and when they
will fail.

There are inevitiably limits on everything, from SMTP message sizes to
FTP file sizes.  Those limits involve administrative fiat as well as
external considerations (e.g. physical disk) and other such limits as
protocol limits.  If the IETF would say "No SMTP or ESMTP message should
be larger than 28 MBytes," then the people trying to move pianos using
virtual FedEx envelopes would be happy....well, I am making the big leap
of assuming that email GUI's would tell users when their harmonicas got
too big to fit in an FedEx or AirBourne envelope.   Really fancy GUI's
could to really fancy things, such as try to use FTP, HTTP, or external
SMTP bodies when offered a piano.

Without a standard maximum SMTP size (and not just a minimum maximum as 
in RFC 1123), really fancy GUI's are impossible, since they can't know
whether a 280 MByte attachment will work.

Note that contrary to some implications, no outfit that I've encountered
uses the same procedures for shipping overnight letters (SMTP) as pianos
(FTP, NSF, rcp).  The choice of motor carrier for the piano and courier
service for the overnight letter is often left to the shipping department.
However, things generally work as well when you put your overnight letter
on a pallet and call the shipping department as when you put your piano
in the FedEx pile on corner of the adminstrator's desk.


Vernon Schryver    vjs at rhyolite.com