Path: utzoo!attcan!uunet!ogicse!ucsd!ucbvax!THUMPER.BELLCORE.COM!nsb
From: nsb@THUMPER.BELLCORE.COM (Nathaniel Borenstein)
Newsgroups: comp.soft-sys.andrew
Subject: Re: Mail munging
Message-ID: <sb_4ING0M2YtQ657gw@thumper.bellcore.com>
Date: 26 Oct 90 14:15:53 GMT
References: <Ub9rqKwB0KGW8aN0Nz@holmes.parc.xerox.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 15

You can use the AndrewSetup line 

AMS_NoDomainPreferredOnLocalMail: 1

which may or may not be what you want.  It will make "janssen" validate as

Bill Janssen <janssen>

rather than

Bill Janssen <janssen@parc.xerox.com>

If that's not what you want, then I'm not sure how to help.  (Of course,
if you do this, you'll have to make sure your sendmail rewrites the
headers before external delivery.)