Mailman 3 - Dedicated Mailman 3 installation. Unlimited lists/configuration. Free subdomain at mailman3.com. Dedicated support for list admins.

Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.

Eduflow - Digital learning that actually teaches students something

Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.

Kialo - Kialo is the platform for rational debate. Empowering reason through friendly and open discussions.