See http://www.mail-archive.com/ for an excellent example of one way that
anyone, anywhere can make the archives of any list web-accessible to the
entire Internet world, even if the list is configured to maintain no
archives. A list which is configured (or operated in a manner) to accept
subscription requests from addresses whose owners are not personally known
and trusted by the list owner is vulnerable to exploitation by users of
this and similar services, regardless of any other safeguards which the
owner might have in place.

The operator of this service may have a pure heart and noble intentions,
but the manner in which the service is implemented makes it vulnerable to
exploitation.

--
Paul Russell
Senior System Administrator
University of Notre Dame