When configuring the ShareScan Exchange Connector using EWS, HTTP error 407 (Proxy authentication required) appears.
Proxy server connection may not be configured correctly for access to the Exchange server. This error is returned when accessing a Web site through a proxy server that has access control enabled and using Basic Authentication.
The Web Proxy, through a 407 HTTP response, requests credentials from the browser client (or downstream Proxy Server). The client provides the credentials, or in the case of a downstream Web proxy, the proxy server may provide the credentials itself.
If the credentials used by the client or by the downstream proxy server are not allowed by the upstream proxy server, this error will be displayed.
Error 407 may be the Exchange server replying back that authentication is required for the connection from the proxy server to succeed.
The following two Microsoft articles may help to configure the Sharescan server's internet/network proxy connection:http://support.microsoft.com/kb/271361