I would like to propose a solution to the looming religious war:
Some people are serious about wanting to see every message that crosses the ietf domain, and will offer violence to anyone who wants to keep their daily dose of spam away from them. Others (well, me. I follow ietf and ietf-announce for my own entertainment and education. I don't mind if you filter on "bigger dick".) will be willing to accept the server-based filter, in order to spare their inbox.
Would it be possible to somehow flag messages as "valid" or "bogus" (or maybe "Holy Writ" or "Message from Satan"), and then allow subscribers to set their systems to automatically filter on these labels, if they care?
Of course, if I wanted the mail server to work harder, I would suggest that the system keep track of each subscriber's preference and either send or pass, thus saving the bandwidth.
I would very much like it if this could be implemented. I get enough spam as it is; I don't care to receive even more through the IETF lists. The problem with just tagging the spam is that it still wastes bandwidth, and to add insult to injury, the extra anti-spam headers waste even more bandwdith. Fortunately, it isn't as bad as I expected, for instance your message contains:
X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on ietf-mx.ietf.org
X-Spam-Status: No, hits=1.1 required=5.0 tests=PENIS_ENLARGE autolearn=no version=2.60
And before anyone asks: yes, I care because I regularly connect over GPRS and my (spam) filtering happens client-side.
I don't believe keeping track of the recipient's spam reception preference is a lot of work for the mailing list server: simply set up two lists, one that checks for spam, adds the headers and forwards, and one that checks for spam, doesn't add headers and forwards on non-spaminess.
Altenatively, wouldn't it be possible to create a system where list members sign their message, and when the signature is recognized, the message is automatically flagged as "not spam"?