Very easy to use and quick to setup. I have used it personally.
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Mailman 3 - Dedicated Mailman 3 installation. Unlimited lists/configuration. Free subdomain at mailman3.com. Dedicated support for list admins.
Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
GroupServer - Email lists, with an integrated web interface, and control.
Nakisa Hanelly - Nakisa Hanelly is a cloud-native organizational design and workforce analytics solution technology developed to get ahead of the dynamic world of work and optimize employee performance and motivation.