Send a message to the client, prefixed and postfixed by the current HeaderBlock and TrailerBlock characters.
The data is not guaranteed to be received after this function is called. All data is buffered internally; completion of this call does not signify reception of data.
Function requires a running message loop (see RunMessageLoop).
Blocking: Function does not block.
Events: If an error occurs during the send operation, an ClientErrorReceived event results, containing the error message indicating why the send attempt has failed.