getting sendmail to add Return-Path: header

[David Banning]

> > > I am not sure what I did, or what the purpose of Mprog is.
> > 
> > The prog mailer is generally for aliases that pipe mail into programs
> 
> It also applies to pipes in .forward files, so if David has a
> "|procmail" entry in his .forward, that will force sendmail to use the
> prog mailer instead of local.  FEATURE(local_procmail) in your .mc is a
> better solution, which will tell sendmail to use procmail as the local
> delivery agent, so you don't need .forward at all.

Yes, I tested that. So the mystery is solved, it seems. Thanks Matthew and 
Dan for your help -