Re: [Asrg] Ban the bounce; improved challenge-response systems

[Vernon Schryver <vjs@calcite.rhyolite.com>]

> From: J C Lawrence <claw@kanga.nu>

> wayne  <wayne@midwestcs.com> wrote:

> >>> their ears while I ask) how many MTAs (besides Qmail with 
> >>> "Return-Path" headers) make this info available to the MUA ?

Sendmail has added Return-Path for years, and the UNIX style From_
for decades.

> ...
> >> And in those cases, how many MUAs would know about it ?
>  
> >> Proximal to zero.

> ...
> I'm not aware of any MUAs (possible exception of GNUs, ...

What does it mean for an MUA to know about the envelope sender?

The decades old BSD and SV `mail` programs know about the UNIX
style From_ header with its envelope sender value, and in fact require
it in mailboxes.  I suspect far newer MUAs such as Netscape when
running on UNIX-like systems are similar.
The old `mail` also knows about Return-Path in the sense of displaying
the header unless you tell recent versions to suppress it.

What about the decades old UNIX `vacation` program?  If it is an MUA,
then it certainly knows about the envelope sender, because that's
where it directs its messages.


Vernon Schryver    vjs@rhyolite.com
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