SYMPA -- Systeme de Multi-Postage Automatique

SYMPA is an electronic mailing list manager. It is used to automate list
management functions such as subscription, moderation and management of
archives. SYMPA also manages sending of messages to the lists, and
makes it possible to reduce the load on the system. Provided that you
have enough memory on your system, Sympa is especially well adapted for big
lists. For a list with 20 000 subscribers, it takes 5 minutes to send a
message to 90% of subscribers, of course considering that the network is
available.

WWW: http://www.sympa.org/