On Fri, Mar 26, 2004 at 05:48:01PM +0000, David Woodhouse wrote:
We need to make the solution to the forwarding problem as unintrusive as
possible for the forwarding hosts.
SMTP already has a potential answer -- the 551 result code which gives
an alternative address to use instead of the address which was given in
the RCPT TO: command.
I think the SPF specification should make it clear that a forwarding
host, upon receiving mail from a domain with an SPF record, MAY return a
551 result code with the forwarding address.
And of course that the SMTP client responsible for _sending_ such mail
MUST deal appropriately with such responses, by delivering the mail in
question to the newly-provided forwarding address.
This cure may be worse than the disease. As I understand it, you have
totaly disallowed forwarding. Instead the former forwarding machine
is to return a 551 and the new address. But, how does the forwarding
machine discover the new address? What if forwarding is to more than
one address. What if the purpose of forwarding was to shield the
final address from discovery?
--
dwmw2
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