Lumen started life as a group discussion platform akin to Google Groups, Mailman or Sympa. Since then, it’s gained some powerful extras. An outline of its features:

  • Open-source (under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported)
  • Hosted using Heroku (for the web interface, free in initial case), Amazon S3 (for file attachments, typically free or a few pennies per month) and Virtualmin (for the mail sever, requires a low-end VPS at a cost of a few pounds per month)
  • Designed for custom domains (group email addresses of the form yourgroup@​yourdomain.​org)
  • Sends and receives mail via regular SMTP and IMAP accounts on Virtualmin
  • Dual web/​email access
  • Extensible member profiles
  • Flexible digest engine
  • Events calendar
  • Daily summaries of news stories tweeted by group members via news​.me integration
  • Maps of people, organisations etc
  • Google Docs integration
  • Facebook style walls