hMail Server
Open Source
hMailServer is a free open source email server for Microsoft Windows.
MDaemon Messaging Server
Commercial
MDaemon Messaging Server is an e-mail server software for Windows.
Microsoft Exchange Server
Commercial
Microsoft Exchange Server is a mail server and calendaring server.
Compare mailcow with alternatives
Compare hMail Server and mailcow and decide which is most suitable for you.
Compare Microsoft Exchange Server and mailcow and decide which is most suitable for you.
Compare MDaemon Messaging Server and mailcow and decide which is most suitable for you.