12.1 protocol (Exchange update is needed). Or wait for N900 MfE client update. I am really sorry about this bug. The keywords to detect it: MS-ASProtocolVersions: 1.0,2.0,2.1,2.5,12.0 AS-LIB: Created factory for version 2.5 After client update (w/o server update) you will see: MS-ASProtocolVersions: 1.0,2.0,2.1,2.5,12.0 AS-LIB: Created factory for version 12.0 After Exchange update you will see: MS-ASProtocolVersions: 1.0,2.0,2.1,2.5,12.0,12.1 AS-LIB: Created factory for version 12.1