anchor.diff:      }
   
       _currentAction = _actionAuthenticateLoginPassword;
  -    sendCommand(base64.encode(options.username.codeUnits));
  +    sendCommand(convert.base64.encode(options.username.codeUnits));
     }
   
     void _actionAuthenticateLoginPassword(String message) {
  
positive.code:       envelope._isDelivered = true;
  
        onIdle.listen((_) {
          _currentAction = _actionMail;
          sendCommand('MAIL FROM:<${Address.sanitize(_envelope.from)}>');
        });
  
negative.code:     var recipient;
  
      // We are processing the last recipient.
      if (_recipientIndex == _allRecipients.length - 1) {
        _recipientIndex = 0;
  
        _currentAction = _actionRecipient;
        recipient = _allRecipients[_recipientIndex];
      }
  
      // There are more recipients to process. We need to send RCPT TO multiple times.
      else {
        _currentAction = _actionMail;
        recipient = _allRecipients[++_recipientIndex];
      }
  
      sendCommand('RCPT TO:<${Address.sanitize(recipient)}>');
  