Rackspace

Basic

100% Uptime Guarantee
24x7x365 Fanatical Support
25GB Mailboxes
Free & Easy Migrations
Instant Messaging Webmail Only
Outlook desktop, mobile, and webmail access
Premium Anti-Spam and Anti-Virus
Shared Calendaring Webmail Only
Shared Contacts Webmail Only

Plus

Add File Storage, ActiveSync, Office-compatible apps & IM
24x7x365 Fanatical Support
Free & Easy Migrations
Works with Outlook & Mobile
Premium Spam & Virus
Webmail
30GB File Storage
Mobile Sync (ActiveSync)
Shared Calendaring/Contacts
MS Office-Compatible Apps
Instant Messaging

Microsoft Exchange

100% Uptime Guarantee
Email address @ your domain
100GB Mailboxes
Instant Messaging
Real-time Outlook, OWA & Mobile Synchronization
Outlook desktop, mobile, and webmail access
Support for Migrations
Premium Anti-Spam and Anti-Virus
Shared Calendaring
Shared Contacts
Admin Control Panel
Distribution Lists (Group Lists)
Resource Mailboxes
Send-As Permissions

Email & Exchange

Add File Storage, ActiveSync, Office-compatible apps & IM
24x7x365 Fanatical Support
Free & Easy Migrations
Works with Outlook & Mobile
Premium Spam & Virus
Webmail
30GB File Storage
Mobile Sync (ActiveSync)
Shared Calendaring/Contacts
MS Office-Compatible Apps
Instant Messaging
Admin Control Panel
Distribution Lists (Group Lists)
Resource Mailboxes
Send-As Permissions