The Standard Edition of SBS includes Windows SharePoint Services for collaboration, Microsoft Exchange server for e-mail, Fax Server, and the Active Directory for user management. The product also provides a basic firewall, DHCP server and NAT router using either two network cards or one network card in addition to a hardware router.

• Only one computer in a domain can be running Windows Server for Small Business Server.
• Windows Server for Small Business Server must be the root of the Active Directory forest.
• Windows Server for Small Business Server cannot trust any other domains.
• Windows Server for Small Business Server is limited to 75 users or devices depending on which type of CAL.
• Windows Server for Small Business Server is limited to 4GB of RAM (Random Access Memory).
• A Windows Server for Small Business Server domain cannot have any child domains.
• Terminal Services only operates in remote administration mode on the server running SBS, and only two simultaneous RDP sessions are allowed.

The Premium Edition of SBS includes the above plus the following:

• Microsoft SQL Server
• Microsoft Internet Security and Acceleration Server

The Standard Edition of Exchange includes Microsoft Exchange server for e-mail only (no Fax Server, no Active Directory). Exchange Standard Edition is designed to meet the email messaging and collaboration requirements of small and medium corporations.

• Integrated support for mobile devices
• Ability to be configured as a front-end server for Microsoft Outlook Web Access, Microsoft Outlook Mobile Access, Microsoft ActiveSync, Post Office Protocol 3 (POP3), Internet Message Access Protocol (IMAP), and Simple Mail Transfer Protocol (SMTP)
• One storage group can be created on a server
• One mailbox store database and one public folder store database that can be accessed by using MAPI and Outlook Web Access
• Up to four more public folder store databases that are accessible only programmatically
• Maximum 16-gigabyte (GB) database limit per database (75 GB with Microsoft Exchange Server 2003 Service Pack 2)
• Exchange clustering is not supported
• X.400 connector is not included

The Enterprise Edition of Exchange is designed for large enterprise corporations. With Exchange Enterprise Edition, you can create multiple storage groups and multiple databases. Exchange Enterprise Edition provides an unlimited message store that removes the constraints on how much data a single server can manage.

• Four storage groups
• Five databases per storage group
• 16 terabyte database limit, limited only by hardware
• Exchange clustering is supported
• X.400 connector is included