检查代理是否支持smtp

Question

我只是想知道我是否有正确的代码来检查代理是否支持SMTP。我不是垃圾邮件发送者，也不是随意让我感兴趣的东西。我有这个测试：

    //host = proxy IP address
    public static void can_mail(string host)
    {
        MailMessage msg = new MailMessage();
        msg.Body = "Email is working!";
        msg.From = new MailAddress("me@whatever.com");
        msg.IsBodyHtml = false;
        msg.Subject = "Mail Test";
        msg.To.Add(new MailAddress("myemailaddress@myserver.com"));

        try
        {
            SmtpClient client = new SmtpClient();
            client.Host = host;
            client.Port = 25;
            client.EnableSsl = false;
            client.Send(msg);
            Console.WriteLine("{0} connected, mail probably works?", host);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }

        Console.Read();
    }

我错过了什么吗？