[Mimedefang] How to change envelope sender?

[Les Mikesell]

On Fri, May 3, 2013 at 12:56 PM,  <kd6lvw at yahoo.com> wrote:
>
>> The problem case is where a spammer discovers that sending to an
>> address will generate a bounce and sends with forged 'from' addresses
>> that are intended as the eventual targets.   So there is potential for
>> damage, but it doesn't necessarily override the responsibility to
>> deliver or report failures.
>
> The above is not only a backscatter problem but the fundamental flaw in challenge-response systems (because to be useful, the challenge message must quote some part of the message under challenge -- even if it's just the subject line).
>
> Backscatter for the most part is not a problem because it has a simple solution:  Message source authentication, with varying implementations and degrees of success - SPF, DKIM, MTX, PGP-signatures, etc.

Various degrees of failure would be a better description....

--
  Les Mikesell
    lesmikesell at gmail.com