it occurs to me that most of the methods that have been proposed
for filtering spam from mailing lists have a lot in common with NATs.
actually, have more in common with firewalls.
I beg to differ. People install firewalls to filter their own incoming
and/or outgoing traffic. Personally I think firewalls are overrated,
but people can filter traffic on their own networks if they want to,
using whatever criteria they think best.
Those who are complaining about spam on this list have the ability to
filter their own incoming traffic. What they're wanting is for someone
else to filter their traffic for them, and for everyone else on the list
also, using poorly-chosen filtering criteria on which there's no consensus.
Keith