Best On-Premises Mail Servers

KumoMTA is an Open-Source, enterprise-grade email message transfer agent (MTA) software for sending high-volume, business-critical emails. KumoMTA is typically chosen by high-volume email users looking to replace PowerMTA, Momentum, or traditional Open Source MTAs. KumoMTA offers high-performance message relay to the tune of millions of messages per hour per server, combined with extreme flexibility and configurability through its use of a Lua scripting engine for configuration and message management. For more information on KumoMTA see our Sourceforge project page.

Secure, enterprise-style email, calendar & collaboration without the high cost. Kerio Connect delivers all the features and functionality for collaboration and messaging solution without the complexity and high price tag of other systems. Email is integrated with shared calendars and scheduling, contacts management, tasks, notes, shared and public folders, and instant messaging. Synchronize messages by direct push to your choice of mobile device via Microsoft ActiveSync. Instant Messaging is XMPP-compatible and can be used from various 3rd party chat/IM applications on desktop and mobile phones. You can install Kerio Connect in 10 minutes and users can be up and running in just 10 minutes more. Kerio Connect can be deployed on-premises or in partner-hosted cloud environments. Deploy for users on Mac, Windows, or Linux; plus full support for Outlook (Windows and Mac) and many other IMAP or POP compliant email clients.

SmarterMail is the ideal Microsoft Exchange alternative. It’s the only business email server on the market that offers native support for Exchange protocols: MAPI, EWS, and EAS, without requiring any additional software or plug-ins for Microsoft Outlook or other desktop or mobile clients. It delivers all the features of Exchange at a fraction of the cost. SmarterMail also includes audio/video group chat and Online Meetings for team collaboration at no extra charge. Its newest feature, the SmarterMail Marketplace, enables seamless integration with platforms like OnlyOffice, Collabora, and AI tools such as OpenAI’s ChatGPT. Available for both Windows and Linux, SmarterMail has lower hardware requirements, superior stability, and reduced maintenance costs. It’s the perfect solution for businesses of any size or industry seeking Exchange-level functionality, without the high costs.