3.2.4.1 Authenticating to a Relay Server

When a client connects to a relay server which implements a local store for the client, the client SHOULD request retrieval of the stored messages from the relay server. To do this, the client MUST perform both device and account authentication and device and identity registration with the relay server by initiating the SSTP Security protocol exchanges as specified in [MS-GRVSSTPS].

Once a client has authenticated with the relay server, the authentication remains valid for the duration of the SSTP connection (1).

The client higher-layer retains all application-assigned identification information, such as account, device, and identity URLs. For clients that have finished an initial authentication registration exchange with a relay server, the client retains the authentication token assigned by the relay server to the account/device and account/identity pairs.