moore@cs.utk.edu (Keith Moore) (07/15/89)
[I've been working on a follow-up to the suggestions by Goodfellow, Vixie,
and subsequently by Kleinpaste, but there are lots of cases to consider,
and it's really difficult to think of everything. So I thought I'd take
a step back and define some general goals. Here's what I have come up
with so far. Comments?]
Goals for successful gatewaying of electronic mail messages (in general):
(Roughly in decreasing order of importance)
1. The first responsibility of a mail gateway is to either:
a) to convert an incoming message and arrange for delivery to its
recipients via the destination network, or
b) to report failure of delivery to the originator if such conversion
is not possible, for example, if the message body (for non-text
messages), or an envelope recipient address could not be converted.
2. The gateway should make reasonable attempts to ensure that all components
(e.g. envelope addresses, headers, and message body) of the gatewayed
message are within accepted standards for the destination network, and
if possible, also within the usual conventions for the destination
network.
3. Ideally, the gateway should arrange that notification of delivery
failure on the recipient's network will be returned to the originator.
If this is not possible, such notification should be returned to the
gateway postmaster.
4. Ideally, a recipient of the message should be able to reply to the
message using his UA's "reply" or similar command. The gateway should
arrange that such replies will be sent to the "correct" reply address(es)
according to the conventions of the originator's mail system.
5. Gateways should preserve information which may be useful to a human
in tracing the path that a message traversed in reaching its
destination, and in determining an appropriate reply address should
the gateway be unable to provide one.
6. Gateways should make a reasonable attempt to ensure that all header
and envelope addresses are "correct" according to the standards and
conventions of the destination network, for those headers that are
likely to be interpreted by mail-handling programs. "Correct" means
that the addresses are likely to be interpreted correctly by mailers,
not simply that the addreses are syntatically correct.
7. Gateways should never knowingly pass invalid envelope or header addresses
on to the destination network. If, for instance, an address cannot be
translated appropriately according to the standards of the destination
network, it should be hidden from mail-handling programs, and the
original address preserved in an appropriate place (e.g. an extension
message header) for interpretation by humans.
--
Keith Moore Internet: moore@utkcs2.cs.utk.edu
University of Tenn. CS Dept. BITNET: moore@utkvx
107 Ayres Hall, UT Campus UT Decnet: utkcs2::moore
Knoxville Tennessee 37996-1301 Telephone: +1 615 974 0822