On Tue, 2004-03-23 at 13:30 +0000, David Woodhouse wrote:
Basically, the question you need to ask is "Is the flawed assumption of
SPF going to cause this message to be rejected because I'm sending it
from this particular IP address". And that question _is_ one that can be
answered in the output stage of your MTA.
OTOH if you're asking yourself this question at input time, you can just
give a 551 result code with the new destination address, and let the
sender deal with it.
Widespread application of this would mean that SPF-publishing domains
need to behave appropriately upon receiving a 551 response -- but they
were the ones who volunteered to change the world, so that's not as
onerous a requirement as _any_ requirement we place on uninterested
third parties who do forwarding.
--
dwmw2