grommunio is described as '(formerly known as grammm) efficiently combines all requirements of modern, digital communication and collaboration' and is a Mail Server in the office & productivity category. There are more than 10 alternatives to grommunio for a variety of platforms, including Web-based, Linux, Self-Hosted, SaaS and Windows apps. The best grommunio alternative is Nextcloud Hub, which is both free and Open Source. Other great apps like grommunio are Kolab, Zimbra Collaboration Suite, SOGo and Kopano.
Nextcloud is the most deployed on-premises file share and collaboration platform. Access & collaborate across your devices. As fully on-premises solution, Nextcloud Hub provides the benefits of online collaboration without the compliance and security risks.
Kolab provides a FOSS communication & collaboration solution that can be completely self-hosted. Take back control of your data and access it via the webinterface, or existing mobile & desktop clients.
Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more. With the most innovative web application available today, Zimbra boosts the productivity of users on any desktop and dramatically reduces TCO compared to legacy platform vendors.
SOGo is groupware server with a focus on scalability and open standards.
SOGo provides a rich AJAX-based Web interface and supports multiple native clients through the use of standard protocols such as CalDAV, CardDAV and GroupDAV.Share your calendars, address books and mails in.
Kopano puts an email, video meetings, calendaring, and file sharing solution within one single interface.
Exchange business-class email helps increase user productivity while protecting your data. Get it as a hosted service or run it on your servers.
Kolab Now provides a suite of intuitive apps in a user friendly environment to make your day to day online comms easier, smarter and most importantly; secure.
Horde Groupware is a free, enterprise ready, browser based collaboration suite. Users can manage and share calendars, contacts, tasks and notes with the standards compliant components from the Horde Project.
Collabtive is a cloud based groupware, easy to use and efficient for your projects.
The OX App Suite by Open-Xchange is web-based platform offering a suite of apps like an email client, calendar, contacts magement, cloud storage with synchronization and productivity apps for word processing, spreadsheets and presentations.
OpenChange aims to provide a portable Open Source implementation of Microsoft Exchange Server and Exchange protocols.
Kerio Connect makes email, calendars, contacts and task management easy and affordable. With Kerio Connect, you have immediate, secure access to your communications anytime, anywhere, on any device - without complexity or expensive overhead.
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