WebDav (Web Distributed Authoring and Versioning) is an extension of HTTP that facilitates creating, changing, and moving documents on a server as well as editing properties of a file. WebDAV can be used to access Microsoft Exchange mailboxes over HTTP connectivity. Each folder, message, calendar event, contact, and so on, has a URL that can be used to access it. The IM and Presence Service can use WebDAV to gather information on calendar events. WebDAV is deprecated in Microsoft Exchange 2010 and beyond.
Figure 1. Microsoft Exchange Integration with WebDAV over the IM and Presence Service