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majordomo system has been installed and in use at SLAC for some time.
http://www.slac.stanford.edu/comp/net/majordomo/majordomo-basic.html
LWGate software at SLAC provides very limited web access:
http://www.slac.stanford.edu/cgi-bin/lwgate/
People often refrain from using mailing lists because of the fear of "spamming" people not interested in a specific topic and instead just send e-mail to a random list of people.
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Hypernews has been used extensively by Babar, and is now also used by Geant4, CMS and LSST.
http://hypernews.slac.stanford.edu/
It is very popular with users, especially the threaded discussions, ability for users to browse existing discussions and opt-in to those that interest them and the ability to receive and respond to messages either via the web or e-mail. The implementation of hypernews is somewhat old and no longer being actively developed.
Implementation: Perl
PHPBB
One of the most popular open-source forum distributions. Used by many sites including RootTalk: http://root.cern.ch/phpBB3/. Does not support threaded discussions.
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Open-source forum software: http://fudforum.org/forum/
Already in use at SLAC for some forums like http://forum.linercollider.org/
Slightly more features than phpbb (http://www.forummatrix.org/compare/FUDforum+phpBB). The forum supports all of the features we want (and many more). We have not enabled ability to respond to topics via e-mail, since it requires setting up a new e-mail address for each forum, but it is supported and could be handled in the same way that we currently deal with hypernews forums.
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Confluence "Community Bubbles" plugin
https://www.adaptavist.com/display/Bubbles/Forums
Adds forum capabilities to confluence. Currently installed on confluence-new. Integrates with confluence login mechanism and integrates nicely with other confluence functionality. Anyone who can edit a page can add a forum using the {forum} macro. Does not support all of the functionality of a dedicated forum, for example e-mail notification is based on confluence page or space views, cannot respond to topics via e-mail.
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