favor

[Eric Kjeldergaard]

>  Archiving messages without telling subscribers
> about it and requiring them to agree with it only invites trouble.

http://lists.freebsd.org/mailman/listinfo/freebsd-questions

This is the page on which you sign up.  You'll notice it says this in the about:

  This is the mailing list for questions about FreeBSD. You should not
send "how to" questions to the technical lists unless you consider the
question to be pretty technical.

  To see the collection of prior postings to the list, visit the
freebsd-questions Archives.

Since we are discussing implicit contracts, I would think that the
announcement that the collection of prior postings is linked to and
mentioned/described to be reasonable notification that the mailing
list gets archived.

-- 
If I write a signature, my emails will appear more personalised.