Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Membee - Membee is web-based membership management software.
Groups.io - Email and web based discussion group software, includes archiving, emails, wiki, polls, file...
Galette - Galette is a membership management web application towards non profit organizations.
Gaggle Mail - Gaggle Mail is a simple and easy to use email list manager.
Bigtent - BigTent is a web-based organization and communication portal for groups.