Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.
Groups.io - Email and web based discussion group software, includes archiving, emails, wiki, polls, file...
Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.
Gaggle Mail - Gaggle Mail is a simple and easy to use email list manager.
Creativity 365 - Cross-device content creation suite