Microsoft 365 - Boost your productivity with reliable access anywhere with services like email, calendar, file sharing, meetings, instant messaging, and Office Online
mailcow - An open source mailserver suite.
Apache OpenOffice - Apache OpenOffice is an open source, office document productivity suite.
SmarterMail - SmarterMail is a next generation email management server that is offering several business collaboration and communication features as well.
SSuite Office - SSuite Office is called to be one of the most accomplished software developers for both beginners and professionals alike.
hMail Server - hMailServer is a free e-mail server for Microsoft Windows.