Aliasource has released a plugin to import PST files in Thunderbird. It is released under the GPL, and is part of Aliasource's OBM collaboration tool, which also has a community site.
OBM offers a broad range of possibilities, from Groupware to CRM, from messaging to project management, and even a Synchronization framework.

Aliasource offers services around OBM, but all sources can be downloaded. OBM is built on solid, proven software such as OpenLDAP, Cyrus-IMAP, Postfix, Clam/AV, Spamassassin, Funambol, apache, Mysql or Postgresql, PHP, etc

As seen on Linuxfr

Signal-Spam is a french anti-spam intiative. An english version of the site is available, but some documents and website parts are only available in french.
The goal is to have a national anti-spam platform, which is notified by a user when (s)he has received spam. Users need to first create an account on the platform as it doesn't accept anonymous notifications. Simple registration (email+password) are for user simply wishing to report spam. Users who want their reports to be usable in a legal action need to register fully (more detailed contact information).

A plugin for Outlook and an extension for Thunderbird 2.0 have been developed, and an API is available to develop further tools, such as this Python script usable with Mutt.