Horde
Horde Groupware is a free, enterprise ready, browser based collaboration suite.
19 Alternatives To Horde
Cypht
All your E-mail, from all your accounts, in one place. Cypht is like a news reader, but for E-mail.
G Suite
Google’s encompassing suite of cloud-based business apps.
Kolab Community
Kolab Groupware is a secure, scalable, reliable, flexible, full-featured collaboration suite.
Mail-in-a-box
Mail-in-a-Box provides webmail and an IMAP/SMTP server for use with mobile devices and desktop mail software and also includes contacts and calendar synchronization.
Mailpile
Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
NeutronMail
Self-hosted server for the ProtonMail client.
Outlook
Organize your world. Outlookâs email and calendar tools help you communicate, stay on top of what matters, and get things done.
ProtonMail
Secure email with absolutely no compromises. Get your free encrypted email account today.
Rainloop
RainLoop is a web based email client.
Roundcube
Web-based IMAP email client
SOGo
SOGo is groupware server with a focus on scalability and open standards.
Squirrelmail
SquirrelMail is a standards-based webmail package written in PHP.
Turing Email
Turing. Modern email has arrived. Turing Email supports email providers including Google Apps, Outlook, Yahoo Mail, iCloud Mail, and AOL Mail. Join our exclusive network.
Webmail Lite
Open Source WebMail Lite is a free community edition of full-featured WebMail Pro server applicatio…
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.
Zimbra Collaboration Suite
Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more.
Zoho Mail
Zoho Mail is a webmail service built with the needs of a modern business in mind.
iRedMail
A fully fledged, free email server solution, an open source project (GPL v2).
mailcow dockerized
An open source mailserver suite.