How to validate SMTP server

Question

I am working on a project where I have to validate the given SMTP server i.e in a textbox user will provide the detail and then he will click on a test button. I want to check w

Answer 1

You might want to improve on this quick code with proper exception handling and maybe also setting the timeouts - it takes about 15 seconds to fail if it can't connect but that might be a limitation of the TCP/IP handshaking.

And sending a QUIT command as Curt suggested would be nice.

private bool ValidSMTP(string hostName)
{
    bool valid = false;
    try
    {
        TcpClient smtpTest = new TcpClient();
        smtpTest.Connect(hostName, 25);
        if (smtpTest.Connected)
        {
            NetworkStream ns = smtpTest.GetStream();
            StreamReader sr = new StreamReader(ns);
            if (sr.ReadLine().Contains("220"))
            {
                valid = true;
            }
            smtpTest.Close();
        }
    }
    catch
    {

    }
    return valid;
}