Outlook Web Access

Outlook Web Access (OWA) is a webmail service of Microsoft Exchange Server 5.0 and later, originally called Exchange Web Connect (EWC). The web interface of Outlook Web Access resembles the interface in Microsoft Outlook. Outlook Web Access comes as a part of Microsoft Exchange Server 2007 and previous versions of Exchange.

OWA is used to access e-mail (including support for S/MIME), calendars, contacts, tasks, and other mailbox content when access to the Microsoft Outlook desktop application is unavailable. In the Exchange 2007 release, OWA also offers read-only access to documents stored in Microsoft SharePoint sites and network (UNC) shares. Microsoft provides Outlook Web Access as part of Exchange Server to allow users to connect remotely via a web browser. Some of the functionality in Outlook is also available in this web "look-alike". The most important difference is that Microsoft Outlook allows users to work with e-mail, calendars, etc., even when a network connection is unavailable, whereas OWA requires a network connection to function. OWA can be used from Internet cafes and any other location that provides connectivity to the Web.

Functionality of the OWA is partly bundled with the use of a Microsoft client operating system and the Microsoft Internet Explorer (IE). The OWA interface available in Exchange 2000, Exchange 2003, and Exchange 2007 is available in two flavors. The so-called "Premium" user interface is rendered for Internet Explorer 5 (for the 2000 and 2003 releases) and Internet Explorer 6 SP1 and later for the 2007 release. The so-called "Basic" user interface (UI) is rendered for other browsers. Some functions, such as Search, are not available in the Basic UI. Since there is no current IE installer available for Mac OSX and no official installer at all for Linux, Linux and many Apple users can only use restricted functionality.

The first component to allow client-side scripts to issue HTTP requests (XMLHTTP) was originally written by the Outlook Web Access team. It soon became a part of Internet Explorer 5.0. Renamed XmlHttpRequest and standardized by the World Wide Web Consortium^[1], it has since become one of the cornerstones of the Ajax technology used to build advanced web applications.