"Margaret" == Margaret Olson <margaret(_at_)margaretolson(_dot_)com>
writes:
Margaret> The rate limiting needs to occur on the sending side,
Margaret> but the receiver needs to know what it is.
But there's no need for the sender to publish the rate limiting
information, because there's little reason for you to trust them. It
make more sense for the sender to simply refer to a rate limit policy
published by their ISP (which could be achieved by an SPF modifier).
The reciever would then query the ISPs rate limiting policy for this
domain and (assuming positive accreditation of the ISP) the recipient
would then believe it.
Obviously the ISP's rate limiting policy would have to specify the IP
addresses that they're responsible for (they can't rate limit mail you
send out via another source) but this is all information that should
be published by the ISP, not the sender.
So I don't believe it belongs in policies published by the sender, but
in a completely new type of policy published by ISPs who send mail on
behalf of their customers.
Though, as I said before, I'd like to see a move towards (return to)
sites originating (and being responsible for) their own mail rather
than relaying through their ISP...
-roy