Due to my inability to create a perfect filter which would block all spam but let all relevant traffic in, we are enacting a new policy for the clisp-list mailing list (clisp-announce and clisp-devel are already member-only).
1. the list is now member-only: you must be subscribed to post, and the messages must come from a subscribed address. Please use the web interface to subscribe all your addresses. You can then disable delivery to all but one address (or all addresses if you read the list on gmane.org).
2. there is an additional way to post to the clisp-list mailing list (for those who hate e-mail or the notion of "subscription"): the "Help" web forum http://sourceforge.net/forum/forum.php?forum_id=3816, whose messages are redirected to clisp-list automatically. You must be logged on to your SF.net account to post.
I know this abrupt change will not make everyone happy, but I see no other way to cut off the spammers.
The only alternative I see is list moderation, and I do not volunteer for this task (anyone does?)
Comments are welcome, both on the list and on the web forum (to test that venue).