Like Mark Drake <[log in to unmask]>, I use a (Mac) Eudora plug-in that allows
the inclusion of arbitrary header fields. And like Mark's, the one I use
also requires you to manually change the settings in order to switch
between using a "Resent-From" header and not using it. The plug-in I use is
named "Eudora RSVP Prefs". I got it from a mirror of the Info-Mac archive.
Here is the brief description of the "Eudora RSVP Prefs" plug-in.
Abstract of INFO-MAC archived encoded Mac binary file
   'comm/inet/mail/eudora-rsvp-prefs-14.hqx'
  Uploaded 01/09/96   5500 bytes
 
From: Andy Fragen <[log in to unmask]>
Subject: Eudora RSVP prefs v1.4
 
This plug-in came out of the frustration of not being able to change the
'From:' header from the standard format user@host (Real name) to anything
else
 
Support for X-Headers
 
Ability to edit the 'From:' field from the composition window.
 
This is freeware.  There are no warranties, expressed or implied.  If you
like it or have other suggestions send email.  Eudora RSVP prefs may be
freely distributed but must be distributed with this ReadMe file.
 
Andy Fragen
[log in to unmask]
http://cctr.umkc.edu/user/afragen/afragen.html
January 7, 1996
 
 
/David M. Rosenberg        [log in to unmask]        1-617-253-8054