The best free alternative to Axigen is Zimbra Collaboration Suite, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Axigen and eight of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Axigen are hMail Server (Free, Open Source), Kopano (Freemium, Open Source), Nextcloud Hub (Free, Open Source) and OpenChange (Free, Open Source).
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.
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.
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.
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.