1. Premium Unlimited Usenet news server services.

  2. Create email discussion lists

  3. Facebook Events enables businesses to organize gatherings, manage invitations and send notifications and reminders to their audience.

  4. Email and web based discussion group software, includes archiving, emails, wiki, polls, file...

  5. TribeScale - The all-in-one platform to manage your teams - Tribescale

  6. handy and feature-rich enterprise multi-device messenger available for server or cloud โ€“ Slack-like, but not Slack-limited

  7. Sympa is an open source (GNU GPL) mailing list management (MLM) software.

  8. FreeLists provides the internet community with Free, no-hassle, high-quality mailing lists

  9. The fastest way to sync your team with ongoing projects

  10. Mattermost is an open source alternative to Slack.

  11. A hosted mailinglist manager service

  12. BigTent is a web-based organization and communication portal for groups.