I have not yet seen a good answer to why we can't resurrect the reverse
source path. Both forward and reverse source routing are currently
deprecated but not banned - all MTAs already are required to deal with
them. MTAs are instructed to ignore source routing for purposes of
delivering mail - this is exactly what we want also. All we want is for
forwarders to start including the reverse source route in the envelope
from. It can still be ignored for bounces, but is what we want to verify
for SPF. Forwarders will have to modify their MTA to add RFROM anyway.
Why not simply prepend the reverse source route like they used to?
I can understand why SPFv1 works the way it does so that forwarders don't
have to change anything immediately. But why are we adding RFROM instead
of resurrecting the existing, already supported (if only to ignore),
feature?
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.