Sendmail is a general purpose internetwork email routing facility that supports many kinds of transfer and delivery methods, including the Simple Mail Transfer Protocol (SMTP) used for email transport over the Internet.

The best free alternative to Microsoft Exchange is mailcow: dockerized, which is also Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Microsoft Exchange and 19 is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Microsoft Exchange are Kolab, hMail Server, Infomaniak kSuite and SOGo.
Sendmail is a general purpose internetwork email routing facility that supports many kinds of transfer and delivery methods, including the Simple Mail Transfer Protocol (SMTP) used for email transport over the Internet.

OBM is a free messaging and collaboration platform useful for just a couple to many thousands of users with strong support for mobile devices.



The Mercury Mail Transport System is a mail server that sends and receives messages on behalf of a group of users on a machine or local area network. Messages from the outside world are received by Mercury and delivered to the users, who can access it at any later point.
MailEnables mail server software provides a powerful, scalable hosted messaging platform for Microsoft Windows.
Xeams is a secure and powerful mail server for that includes a powerful spam filtering engine that eliminates up to 99% of junk email right out of the box. The software offers a flexible approach to email, making it a very user friendly server.
A privacy-first, all-in-one ecosystem that replaces Google Workspace and Creative Cloud. Features encrypted email, cloud storage, and docs, alongside a browser-based 3D animation engine and AI assistant. Your data stays yours.




Simple, easy and secure mail server with a convenient and simple interface. Automatic certificate renewal through Let’s encrypt. Redirect, local storage. IMAP and SMTP.



