Features you get with Microsoft Exchange 2007

Built-in Protection
Anti-spam and Antivirus
Built-in defenses against spam and phishing e-mail as well as additional integrated filtering and multi-engine scanning capabilities provide advanced protection.
Compliance
Controls for messages in transport or requiring retention, and flexible journaling help meet organizational, legal and regulatory compliance requirements.
Business Continuity
New data replication capabilities (local and clustered) keep the system highly available while limiting the need and frequency for tape backup.
Anywhere Access
Web-based Messaging
A rich Outlook-like experience from any Internet connected computer with a supported browser provides encrypted access to the inbox, powerful search, and the ability to view different types of attachments.
Collaboration and Productivity
Enhanced calendaring, out-of-office, resource booking, and meeting scheduling capabilities simplify collaboration and increase productivity.
Operational Efficiency
Performance and Scalability
Improved storage efficiency can be achieved through the extended memory and larger cache of x64-based architecture even as mailbox sizes increase; more efficient routing ensures the best use of bandwidth.