This article at LWN covers one of the repeating questions on the list -
regarding authenticating senders in some way. Its a good summary of the
state of the art:-
http://lwn.net/Articles/63578/
This is a "pay for" LWN article, currently available to subscribers
only. LWN is well worth subscribing to, although all their content
becomes free (much of it starts free - its just some of the content
thats subscription based) after a week. Therefore if you are not a
subscriber and do not wish to become one, you can fire up your computer
on Christmas day and read this one!! [Personally I'll be doing
something else]
Nigel
--
[ Nigel Metheringham Nigel.Metheringham@??? ]
[ - Comments in this message are my own and not ITO opinion/policy - ]