Outlook Web App:
Offline access lets users write messages from their browser while offline, delivering the messages when they reconnect to the Internet. This feature is supported in Internet Explorer 10, Safari 5, and Chrome 16 (or later), all of which support the HTML5 local data storage feature.
User Interface layouts
You can access Outlook Web App with tailored user interface layouts designed for tablets or smartphones. This feature is supported on Windows 8 tablets and in iOS 6 or later on iPhones or iPads.
Apps in Outlook attempt to anticipate your needs and automatically propose actions you might want to take by using the contents of the email message. For example, if an email message contains an address, the Bing Maps app will offer you a Bing tab with a quick link to a map and directions. You can add Apps directly from the Office store within the Outlook Web App.
Users can link multiple entries for the same person and view the information in a single contact card. Contact linking is done automatically, but the user can also manually link and unlink contacts.
Users can now view multiple calendars in a merged view. Entries from each calendar have their own color, to allow users to identify which calendar each entry belongs to. The month view now includes an agenda for the selected day, providing users with helpful information as they review the day's activities.
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Sharing and Collaboration:
Public folders are designed for shared access and provide an easy and effective way to collect, organize, and share information with other people in your workgroup or organization. Public folders help organize content in a deep hierarchy that’s easy to browse. Users will see the full hierarchy in Outlook, which makes it easy for them to browse for the content they’re interested in.
Site mailboxes allow users to collaborate effectively by bringing together Exchange emails and SharePoint documents. For users, a site mailbox serves as a central filing cabinet, providing a place to file project emails and documents that can only be accessed and edited by site members.