Zimbra - Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.
Roundcube - Web-based IMAP email client
Microsoft 365 - Boost your productivity with reliable access anywhere with services like email, calendar, file sharing, meetings, instant messaging, and Office Online
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.
YouTeam - YouTeam is a new, smarter way to outsource.
Mailpile - Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.