Mark Sapiro wrote at <http://mail.python.org/pipermail/mailman-users/2012-November/074415.html>:
I have implemented a simple version of what I think you requested in your post at <http://mail.python.org/pipermail/mailman-users/2012-October/074287.html>.
It is implemented by the attached patch against Mailman 2.1.15.
I have augmented that patch with a timestamp and it now also checks that the hash is no older than mm_cfg.FORM_LIFETIME. See <https://launchpad.net/bugs/1082746> and <http://bazaar.launchpad.net/~mailman-coders/mailman/2.1/revision/1371> for a bug report and the patch which will be released with Mailman 2.1.16.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan