Zimbra Desktop is an offline client that lets you manage various email accounts in one desktop tool. Developed by Zimbra
License: Free Personal
Microsoft Mail and Calendar offers seamless integration with Microsoft 365 and a user-friendly interface, making it ideal for users deeply embedded in the Microsoft ecosystem. In contrast, Zimbra Desktop provides a more customizable, open-source solution that excels in offline capabilities and email management, appealing to users who prefer flexibility and control.