SOGo Alternatives

Web-based IMAP email client

Horde Groupware is a free, enterprise ready, browser based collaboration suite.

RainLoop is a web based email client.

Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.

A fully fledged, free email server solution, an open source project (GPL v2).

Kolab Now provides a suite of intuitive apps in a user friendly environment to make your day to day...

Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more.

Google's encompassing suite of cloud-based business apps.

Secure email with absolutely no compromises. Get your free encrypted email account today.

freemium €5.0 / Monthly (user - 5 GB)

Linux directory, domain, mail, gateway and infrastructure server for SMBs.

SquirrelMail is a standards-based webmail package written in PHP.

open-source

With Nextcloud enterprises host their own secure cloud solution for storage, collaboration & communication from any device, anywhere.