It appears that in the process, at least some of the message archives have disappeared from the Web. Specifically, Google gave me this URI:
http://www1.ietf.org/mail-archive/ietf-announce/Current/msg27131.html
(So I guess it must have existed at some time), but I cannot access it now -- I get a response indicating "The page you are looking for cannot be found".
The Google search was this: http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=draft-klyne-msghdr-registry-07.txt&btnG=Google+Search
Having pages disappear from the Web somewhat reduces the Web's value: while recognizing that pages at URIs *can* disappear, the value of the Web is much enhanced if they don't, and particularly for email archives where a URI is the easiest and most effective way to refer to a specific message, so I think it's really worth administering mailing lists in such a way that URIs remain persistently dereferencable.
#g
------------ Graham Klyne For email: http://www.ninebynine.org/#Contact