Question

Problem: Have made a small mail program which works perfectly on my developer pc but when put into production it fails.

protected void Page_Load(object sender, EventArgs e)
{
    string smtpHost = ConfigurationManager.AppSettings["SmtpAddress"];
    MailMessage mail = new MailMessage();
    mail.From = new MailAddress(ConfigurationManager.AppSettings["FromMailAddress"]);
    mail.Sender = new MailAddress(ConfigurationManager.AppSettings["FromMailAddress"]);
    mail.To.Add(new MailAddress("[e-mail]"));
    mail.Subject = "Test mail";
    mail.Body = string.Format("Is this mail sent via {0} ?", smtpHost);

    lblMsg2.Text = string.Format("SmtpHost: {0}", smtpHost); ;

    SmtpClient client = new SmtpClient(smtpHost);
    try
    {
        client.Send(mail);
    }
    catch (Exception exception)
    {
        lblMsg3.Text = exception.Message.ToString();
        lblMsg4.Text = exception.InnerException.ToString();
    }
}

I do get the correct mail address and everything on the production server, but nothing ends in my email inbox :-(. I do not receive any exceptions.

I have tried using telnet on the same server and from there I am able to send mails.

I have tried installing WireShark which is looking at the network card on the server and when using telnet I do get the reponse I suspected, but from my program I do not receive anything.

Edited 2012-03-12 @ 09:46 danish time

Have now updated the code to look like this

protected void Page_Load(object sender, EventArgs e) 
{ 
    string smtpHost = ConfigurationManager.AppSettings["SmtpAddress"]; 
    MailMessage mail = new MailMessage(); 
    mail.From = new MailAddress(ConfigurationManager.AppSettings["FromMailAddress"]); 
    mail.Sender = new MailAddress(ConfigurationManager.AppSettings["FromMailAddress"]); 
    mail.To.Add(new MailAddress("[e-mail]")); 
    mail.Subject = "Test mail"; 
    mail.Body = string.Format("Is this mail sent via {0} ?", smtpHost); 

    lblMsg2.Text = string.Format("SmtpHost: {0}", smtpHost); ; 

    SmtpClient client = new SmtpClient(smtpHost); 

    client.Send(mail); 
} 

And quite interesting: Even when inserting an SMTP-server that does definately not exist, I still do not get any errors on my production environment. I do get an exception on my developer pc which basically means that the smtp-server does not exist (which I also expected to get a message about).

Answer 1

Case solved 🙂

And I learned more about IIS!

The IIS was set up to “Store e-mail in Pickup directory” instead of “Deliver e-mail to SMTP server”. Unfortunately I am not that good at IIS and I did not know that there was a setting like that… I am now!

The “double check you configuration settings” from @GarryM was unfortunately not enough for me or my mail-administrator to make us look at the IIS. I am too much a programmer and my mail-adm is too much a network guy 🙂

Thank you everyone for your answers. It was partly because of all your good hints and ideas that I could leave out more and more parts.