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.
Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates
Sympa - Sympa is an open source (GNU GPL) mailing list management (MLM) software.
MailClark - The Slack bot for external communications
MailChimp - MailChimp is the best way to design, send, and share email newsletters.