🚀 go-pugleaf

I manage two Ultrix nodes at different sites.  In both cases I use
elm as my mailer, and I am running an updated version of sendmail.
This is the headers of the E-mail message as received at my home
node eve.phy.albany.edu which runs Ultrix 4.4

>From sdanet@jill.sdanet.org Tue Jan  9 11:42:03 1996
>Return-Path: <sdanet>
>Received: by jill.sdanet.org (8.6.12/Ultrix3.0-C)
>        id LAA14378; Tue, 9 Jan 1996 11:40:22 -0500
>From: sdanet@jill.sdanet.org (SDA Net)
>Message-Id: <199601091640.LAA14378@jill.sdanet.org>
>Subject: Test message... check the headers
>To: timm@jill.sdanet.org (Steve Timm), timm@sdanet.org, timm
>Date: Tue, 9 Jan 1996 11:40:21 -0500 (EST)


And this is the headers of the same E-mail message as received
at jill.sdanet.org, which runs Ultrix 4.2

>From sdanet Tue Jan  9 11:40:25 1996
>Subject: Test message... check the headers
>To: timm (Steve Timm), timm@sdanet.org, timm@eve.phy.albany.edu
>Date: Tue, 9 Jan 1996 11:40:21 -0500 (EST)

As you can see, the later one is missing a "From: " header
and a Return-Path: header.  If such a message is then "bounced"
to a mailing list using the bounce command in elm,  information
about the sender is lost entirely.

This happens on about 1/3 of the messages received at jill.sdanet.org.
They tend to be from machines with older mail software, but not 
exclusively.

Any idea what could cause the difference?  Is an upgrade required
to fix it, or only a few updated mail programs or a sendmail config problem?

Any help is appreciated.

Steve Timm