Chris Haynes wrote:
They often regard the forward-path as:
1) Confidential and/or,
2) Subject to frequent change
In that case they'd use another 2xx resp. 5xx result code, the
privacy details are explained in 2821. But the essential idea
is still that the forwarder either takes the responsibility,
and that MUST include later bounces in my parallel universe,
or it rejects the mail.
I wonder: Do those forwarders who re-use the same mail-from
address use this 251 response?
No, they abuse the system as it is after RfC 2821. That's why
RMX and later SPF were invented: Back to the roots with clear
responsibilities, as far as possible, saving the good bounces.
Bye, Frank (quixotic RMX-SPF-STD 10 evangelist ;-)