GNU Mailman is a mailing list management software. Mailman project was started long time ago before the Millennium. Since its birth it has become the most intelligent tool for handling mailing lists ever. Huge number of companies with Fortune 500 members among them have been using Mailman for years. The new version Mailman 3 brings to us even better user experience and communication power.
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
Sympa - Sympa is an open source (GNU GPL) mailing list management (MLM) software.
Bigtent - BigTent is a web-based organization and communication portal for groups.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.