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