HTTP 403 error is authorization error. This is the same error I am getting when trying to use N900. The company I work for uses client certificates for WinMo devices. When I setup initial sync with ActiveSync I need to enroll and get personal certificate in ActiveSync. This certificate is stored on WinMo device and used to authenticate the device to Exchange server. Check with your IT whether they will generate this cert for you. Vitaly, (or anyone) could you please tell us if MfE supports authentication with client certificate?