[Mailman-Users] Big headers

[alex wetmore]

On Wed, 18 Sep 2002, J C Lawrence wrote:
> > I believe all of the discussion-list type servers (Mailman, listserv,
> > Mercury, Majordomo, et al) use the same mechanism, so the ISPs that
> > are using this technique for stopping spam will have to address
> > legitimate list servers.
>
> Sadly, nope.
>
> SMTP is an unreliable transport.  ISPs have no especial obligation to
> deliver received mail to their addressed users (no matter that those
> users and we may feel differently).

This is not accurate.  SMTP is a reliable transport.  It either deliveres
the message or deliveres an NDR.

>From RFC2821:

	When the receiver-SMTP accepts a piece of mail (by sending a "250
	OK" message in response to DATA), it is accepting responsibility
	for delivering or relaying the message.  It must take this
	responsibility seriously.  It MUST NOT lose the message for
	frivolous reasons, such as because the host later crashes or
	because of a predictable resource shortage.

	If there is a delivery failure after acceptance of a message, the
	receiver-SMTP MUST formulate and mail a notification message.

MTAs which don't accept this level of reliability aren't SMTP
transports.  Ones which bit bucket mail which has too many
recipients are also not SMTP compliant.

alex