Microsoft Exchange is described as 'Exchange business-class email helps increase user productivity while protecting your data. Get it as a hosted service or run it on your servers' and is a Mail Server in the social & communications category. There are more than 25 alternatives to Microsoft Exchange for a variety of platforms, including Linux, Web-based, Windows, Self-Hosted and Mac apps. The best Microsoft Exchange alternative is Google Workspace. It's not free, so if you're looking for a free alternative, you could try mailcow: dockerized or Kolab. Other great apps like Microsoft Exchange are Kopano, hMail Server, Infomaniak kSuite and Zimbra Collaboration Suite.
Google Workspace delivers a cloud-based suite combining Gmail, Calendar, Meet & Drive to enhance collaboration through tools like Docs and Sheets. Offers secure storage options, custom domain emails, and robust management capabilities with 2FA and 24/7 support.
mailcow is a mail server suite based on Dovecot, Postfix, SOGo, Rspamd and other open source software, that provides a modern Web UI for administration.
Kopano puts an email, video meetings, calendaring, and file sharing solution within one single interface.
hMailServer is a free e-mail server for Microsoft Windows. Its used by Internet service providers, companies, governments, schools and enthusiasts in all parts of the world.
Suite for secure email, calendaring, file sharing, chat, and online meetings, offering real-time collaboration on docs, GDPR compliance, customizable branding, renewable energy use, advanced user management, and all data hosted in Switzerland.
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.
Integrates native Active Directory and all essential network services, including domain, mail, gateway, infrastructure, and security roles, for SMBs, offering web-based management, centralized authentication, file server, VPN, and firewall in a single Linux platform.
grommunio (formerly known as grammm) efficiently combines all requirements of modern, digital communication and collaboration.
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.
Axigen provides a multi-tenant, fully integrated, multi-platform, all-in-one email, calendaring and collaboration messaging solution. It grants extensive branding options and is localized in over 29 languages (including right-to-left writing mode).
United States
Germany
EU
Switzerland
Netherlands
Canada
Spain
Italy
Free and open source, and has most of the things you want from Exchange, including shared calendars.