[Mailman-Users] [Mailman-Developers] Sender field

[Neal Groothuis]

> I'd like to work up an unofficial diff to Mailman 2.1 for people like
> Stephen who are willing to give it a try on a live site.  

I'm not sure this is even necessary.

Ezmlm doesn't touch the Sender: header at all, Majordomo sets it to the 
owner of the list, and (AFAICT) Listserv sets it to the list itself. 
This would seem to me to indicate that incidences of mail being returned 
inappropriately to the sender are infrequent, at worst.

The important question would seem to be "what's appropriate?"  From RFC 
2822, 3.6.2: "The originator fields indicate the mailbox(es) of the 
source of the message."   Given this, the definition of the Sender and 
 From headers, and the example given in this section, it seems that 
Outlook's interpretation of the fields ("SENDER on behalf of FROM") is 
reasonable.  Mailman is not the originator of the message, so it should 
not be tampering with the From: or Sender: fields at all.

It might be appropriate for Mailman to add Resent-* headers, depending 
on how one reads RFC 2822, 3.6.6.  I personally don't think it's 
necessary or useful, since list servers add their own List-* headers, 
per RFC 2369.   The Resent-* headers seem to exist for individuals 
resending messages, not automated systems.  This is supported by the 
RFC: "Resent fields are used to identify a message as having been 
reintroduced into the transport system by a user."