ASP.NET

// Send Email to Admin
System.Net.Mail.MailAddress from = new System.Net.Mail.MailAddress("from@domain.com");
System.Net.Mail.MailAddress to = new System.Net.Mail.MailAddress("to@domain.com");
System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(from,to);

    message.Subject = "404 - File or directory not found";
    message.Body = String.Format(
        "The following page generated a 404 error:\n{0}\n",
        Convert.ToString(Request.QueryString["aspxerrorpath"]) );

System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient("mail.domain.com", 2525);

try
{
    client.Send(message);
}
catch
{
}

From: from@domain.com [mailto:from@domain.com] 
Sent: Friday, May 14, 2010 4:50 PM
To: to@domain.com
Subject: 404 - File or directory not found

The following page generated a 404 error: