Re: SPF and bouncing

On Wed, 4 Apr 2012, alan wrote:
> >that means that mailservers have to be prepared to accept
> >unbounceable mail.
>
> the opposite they should accept or reject at their edge, once the
> decision is made though they should not later change their minds.

They can reject *some* of the unbounceable mail at the edge.  But even if
we optimistically assume that SPF-pass mail is bounceable, rejecting an
email (in-transaction, of course) *solely because* it is not bounceable is
a non-starter in 2012.

> what conspiracy??

The "Conspiracy Against Bounces".  I call it that because it is a
substantial change in the ground rules of SMTP that was never codified in
an RFC.  It's just a majority of admins on the ground deciding "We hate
backscatter, and we can fight it the same way we do direct spam.".  The
fact that now any mail accepted at the edge must be delivered all the way
in (unless you break RFC and blackhole) was an accepted consequence.

Note that I support the CAB.  So do you (quite enthusiastically!).

> if worried about forged <>
> BATV is a simple and easily implemented way to reject forged bounces

BATV is a kind of VERP, and VERP interacts poorly with whitelisting and
greylisting.

Lately I've been considering programming my mailserver to automatically
whitelist anyone I send to.  But if the other guy uses VERP, the envelope
recipient I mail to is not the same as the envelope sender who will reply.

---- Michael Deutschmann <[email protected]>