Yakov Shafranovich wrote:
Allow me to explain myself. If instead of DUL lists, ISPs would use MTA
MARK-style in-addr.arpa entries in rDNS for marking dialup accounts (not
the regular rDNS IP check), then you gaining access over your rDNS space
would let you "opt-out" your machine from the list. But if the DUL list
is not accessable to you, then you are forced to route email over their
smarthost or an external MTA.
OK, understood. Unfortunately, the way Comcast operates, along with many
other residential ISPs, users will never gain control over their rDNS
records. I would strongly recommend against suggesting such a hypothetical
in any draft or porposal.
On the other hand, if we produce an integrated proposal encompassing MTAMark
and the full range of SPF, then we can suggest not rejecting a connection on
the basis of MTAMark-style information.