This article explains some important feature differences between Outlook Web App (OWA) Premium and Light versions running on Exchange 2010.

Outlook Web App (OWA) 2010 provides access to email and calendaring over the internet. Its Premium version is much more robust than its predecessor, Outlook Web Access 2007. With nearly all features of the Outlook 2010 client program, the Premium version may quickly become your preferred email access method.

In order to use OWA 2010 Premium, you must meet the following browser requirements:

• Internet Explorer 7 or later
• Mozilla Firefox 3.0.1 or later
• Google Chrome 3.0.195.27 or later (Windows and Mac only)
• Apple Safari 3.1 or later

If you use a Web browser that doesn't support the full set of features, Outlook Web App (OWA) will open in light version. The light version provides fewer features but is still highly usable.

Below is a feature matrix comparison between the Light and Premium versions. Green checks indicate the feature is available in that version; red x buttons mean the feature is not available.

Feature	Light	Premium
Spell Check
Reading Pane
Accessibility for Blind and Low Vision Users
Notifications and Reminders
Weekly Calendar Views
Compose Messages by Using HTML	Only plain text
Calendar Options	Limited to the following features:
	* Show week numbers
	* Set the first day of the week
	* Select days of the week
	* Set day start and end times
Arrange By	Limited to a subset of choices
Right-Click Menu
Drag-and-Drop
Resource Mailbox Management
Voice Mail Options
Favorites
OCS Integration
Public Folders
Share a calendar
Open a shared calendar
Monthly calendar views
Conversation view
Scroll between pages
Retention Policies
Users can create and edit personal distribution lists
Users can create and edit server side rules
S/MIME support
Web ready document viewing
Nickname cache
Message Tracking
Advanced Search
Mailtips
Exchange Control Panel
Attach Message to a Message