Answer : 1. "Microsoft Exchange"
Explanation :

1. Personal email account Microsoft Exchange is usually used to download e-mail to your computer.

2. Microsoft Exchange Server is Microsoft's email, calendaring, contacts, scheduling, and collaboration platform.

3. It is deployed on the Windows Server operating system (OS) for business use.

4. Microsoft designed Exchange Server to provide users with access to the messaging platform from mobile devices, desktops, and web-based systems.