Question

Here’s the code I’m running:

try
{
    var fromAddress = new MailAddress("[e-mail]", "foo");
    var toAddress = new MailAddress("[e-mail]", String.Empty);
    const string fromPassword = "password";
    const string subject = "Welcome!";
    const string body = "This is a test message!";

    var smtp = new SmtpClient
    {
        Host = "mail.foo.com",
        Port = 143,
        EnableSsl = false,
        DeliveryMethod = SmtpDeliveryMethod.Network,
        UseDefaultCredentials = false,
        Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
    };
    using (var message = new MailMessage(fromAddress, toAddress)
                                        {
                                            Subject = subject,
                                            Body = body
                                        })
    {
        smtp.Send(message);
    }
}
catch (Exception e)
{
    Debug.WriteLine(e.InnerException.ToString());
    //Add logging here.
}

When I try to run smtp.Send(message) the following error is fired:

A first chance exception of type 'System.Net.Mail.SmtpException' occurred in System.dll
    System.FormatException: Smtp server returned an invalid response.
    at System.Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read,  Boolean readLine)
    at System.Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine)
    at System.Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller)
    at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
    at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)

What are the probably causes for this error? What should I be looking for?

Answer 1

Are you sure your SMTP port is 143? Default is 25. It looks like it can’t talk with the server correctly first (since the error is in GetConnection).