idSmtp 出现如下错误。(20分)

idSmtp1.AuthenticationType := atLogin;
idSmtp1.UserName := MyUserName;
idSmtp1.Password := MyPassword;
idSmtp1.Host := 'smtp.21cn.com';
idSmtp1.Port := 25;
idMessage1.Subject := 'Test';
idMessage1.From.Address := 'xxxxxx@21cn.com';
idMessage1.Recipients.EMailAddresses := 'xxxxxxx@163.net';
idMessage1.Body.Assign(Memo1.Lines);
try
idSmtp1.Connect();
idSmtp1.Send(idMessage1);
idSmtp1.Disconnect();
except
showMessage('连接失败.');
end;





Mail data refused by AISP, rule [18756].

是不是idsmtp中的认证问题
它有一个属性为AuthenticationType的,它可以设置为atlogin与atNone的,你看一下它们的属性值啦