OWA 2010 and prior is considered non-extensible as far as Microsoft is concerned in the area of doing single-sign-on programmatically. The exception to this would be when a person is in-network and uses their existing network credentials to access OWA through Windows Authentication. Please understand...

Single sign-on applications usually use an ISAPI Extension on Exchange servers in order to swap-out credentials being passed to OWA. This type of manipulation is not supported by Microsoft. In fact any thing which augments the behavior in this way is not supported. While such filters/extensions may have...