Which technology is designed to host calendars, contacts, and e-mail on the server?

Microsoft Host Integration Server is used to integrate Windows systems with mainframe and midrange systems, not for hosting email, calendars, or contacts.

Microsoft Expression Studio is a suite of design tools for creating applications and web content, not a server platform for communication services.

Microsoft SQL Server is a relational database management system used for storing and managing structured data, not primarily designed to host email, calendars, and contacts as its core functionality.

Microsoft Exchange Server is a robust messaging and collaborative platform that provides comprehensive services for email, calendaring, contact management, and task management, making it ideal for hosting these services on a server. It integrates with clients like Outlook to offer a complete solution for communication and scheduling within an organization.