Sometimes mailing list archives have links change (e.g. if you delete an email and then reindex the list)
We should let archive.org index the list archives so we have a backup in case of broken links.
Currently all robots are banned because:
# Disabled crawling for several lists 2005-11-26 to # discourage people from complaining about items they # post on public mailing lists being the first Google # search result about them.
But I don't think this rationale applies to archive.org