Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!think!harvard!seismo!brl-adm!brl-smoke!smoke!pallas@su-pescadero.ARPA
From: pallas@su-pescadero.ARPA (Joseph I. Pallas)
Newsgroups: net.mail.headers
Subject: Re: Mail looping
Message-ID: <1354@brl-smoke.ARPA>
Date: Wed, 26-Feb-86 23:53:03 EST
Article-I.D.: brl-smok.1354
Posted: Wed Feb 26 23:53:03 1986
Date-Received: Sun, 2-Mar-86 19:34:52 EST
Sender: news@brl-smoke.ARPA
Lines: 8

Mark, you of all people should know just how futile it would be to attempt
to resolve the entire destination list of a message using EXPN.  Aside from
the fact that some of the destinations may go outside of SMTP, there's no
guarantee that EXPN will return meaningful information.  Several implementations
don't support it, and most that do don't deal correctly with naming-domain
boundary crossings (including yours).

joe