As regards the mhonarc.org archives, I advocate that the addresses are hidden or, if possible, effectively obfuscated.
So, why can't people who don't like spam just post from bogus addresses? Well, they can. But personally I strongly dislike all arrangements where you need to actively opt out in order to not being targeted with bulk emails. To me, the principally right route is to _encourage_ people to make themselves contactable, rather than feeding the spammers databases with their addresses by default.
-- Gunnar Hjalmarsson Email: http://www.gunnar.cc/cgi-bin/contact.pl