OBM is described as 'Free messaging and collaboration platform useful for just a couple to many thousands of users with strong support for mobile devices' and is a Mail Server in the office & productivity category. There are more than 10 alternatives to OBM for a variety of platforms, including Linux, Web-based, Self-Hosted, Windows and Mac apps. The best OBM alternative is Nextcloud Hub, which is both free and Open Source. Other great apps like OBM are Kolab, SOGo, Zimbra Collaboration Suite and Horde.
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.
United States
Web-based team collaboration suite combining email client, calendar, contact and task tools, CRM, project and file management, file sharing, trouble tickets, Rocket.Chat chat, and Collabora online editing. Offers open source, self-hosted, and SaaS options.
Germany
EU
All-in-one European business email and collaboration platform — email, chat, video conferencing, and office suite in one app. Cloud or self-hosted.
CzechiaEU
Open Source Collaboration, providing integration with your existing Linux mailserver, native mobile phone support, Outlook "Look & Feel" webaccess and stable Outlook sharing (100% MAPI).
Atmail webmail system offers a webmail client, email server platform and mailserver appliance for Linux, Unix and Windows.
Australia
James stands for Java Apache Mail Enterprise Server! It has a modular architecture based on a rich set of modern and efficient components which provides at the end complete, stable, secure and extendable Mail Servers running on the JVM.
Fast, safe, heavy mail solution. Web-client access, LAN or WAN self-hosted server, maintenance-free design. No Windows server and database server required, unlimited mail accounts, storage, attachment size, custom logo. Free for commercial use.
China
Sanwhole Exchange is a server running iMail, iPress and iStore services. iMail is an enterprise-class email server does Microsoft Exchange and Gmail work. iPress sets blog, forums and tickets in one. iStore is an online store.
China
