Sympa plugins
- hidden-attr : Allow user attributes to be marked "hidden" as well as read-only. This allows admins to have user metadata not visible to the user
- rate-limit : Allow rate-limiting scenari to limit users to a specified number of postings per time period
- tracking : Full tracking of message viewing and link clicks via the mail-merge features, with web interface to view stats
- whitelist : Allow whitelists and Modlists as well as Blacklists for posting, managed via the web interface