[Mailman-Users] Non-members allowed to post!

John W. Baxter jwblist at olympus.net
Wed Mar 9 17:04:10 CET 2005

On 3/8/2005 20:27, "Larry Stone" <lstone19 at stonejongleux.com> wrote:

> On 3/8/05 8:45 PM, David Gibbs at david at midrange.com wrote:
>> Sorry if this is a dumb question ... but what header indicates the
>> "envelope sender"?
> None. The "envelope sender" is the return address (MAIL FROM: command) in
> the dialogue between the upstream mail server and your mail server. Then,
> think of your mail server as being a very efficient clerk. It receives the
> mail, opens the envelope, puts what's in the envelope in your inbox, and
> throws away the envelope. Unfortunately by doing so, the envelope is no
> longer available to see. Just as the From: header in a message can be easily
> forged, so can the Envelope Sender.
> Some (but not all) mail servers will added a pseudo-header before the real
> header that shows the envelope sender or an additional header with it. I run
> Postfix and I see it adds both the pseudo-header first (a From line with no
> colon after From) plus a Return-Path: header which also has the envelope
> sender in it. Looking at my mailman archives, the pseudo-From is there but
> not the Return-Path: header.

The "pseudo-From" is part of the mbox file format in which the raw messages
are accumulated for the archive.  The blank line in front of one of them
plus the From (no colon) line itself mark the start of a new message (so
does beginning of file being a From (no colon) line).  [That mechanism is
rather fragile...and is the reason you sometimes see message lines start
with ">From" rather than "From" in your mail stream...some overly protective
programs don't like any "F" at the start of a line.]

Whether the MTA adds a Return-Path: (or other) header is configurable in
most MTAs...I don't know how to set up Postfix to add it to messages sent to
the Mailman input CGI.

One could configure most MTAs to reject mail from Gmane addressed to the
list posting addresses (I also don't know how to do that with Postfix).
That might violate one's agreement with Gmane (I've never seen the

  --John (who doesn't manage any Postfix servers, only Exim)

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