[FTP/FTPS Only] Begins an asynchronous request to supply the password for the previously supplied user-name to log into the FTP server.
An IAsyncResult that references the asynchronous send.
You can create a callback method that implements the AsyncCallback delegate and pass its name to the BeginSendPassword method. The state argument may be used to pass in data that will be passed to the callback method.
For more information please refer to the synchronous version of this method, SendPassword.