Unable to test sending email from .
NET code in Windows Vista Business.
I am writing 
code which I will migrate to an SSIS Package once it its proven. The 
code is to send an error message via email to a list of recipients.
The 
code is below, however I am getting an exception when I execute the 
code.
I created a simple class to do the mailing... the design could be better, I am testing functionality before implementing more robust functionality, methods, etc.
namespace LabDemos
{
    class Program
    {
        static void Main(string[] args)
        {            Mailer m = new Mailer();
            m.test();
    }
}
}
namespace LabDemos
{
class MyMailer
    {
    List<string> _to = new List<string>();
    List<string> _cc = new List<string>();
    List<string> _bcc = new List<string>();
    String _msgFrom = "";
    String _msgSubject = "";
    String _msgBody = "";
    public void test(){
    //create the mail message
    MailMessage mail = new MailMessage();
    //set the addresses
    mail.From = new MailAddress("
[email protected]");
    //set the content
    mail.Subject = "This is an email";
    mail.Body = "this is a sample body";
    mail.IsBodyHtml = false;
    //send the message
    SmtpClient smtp = new SmtpClient();
    smtp.Host = "emailservername";
    smtp.Port = 25;
    smtp.UseDefaultCredentials = true;
    smtp.Send(mail);
    }
}
Exception Message
Inner Exception 
{"Unable to read data from the transport connection: net_io_connectionclosed."}
Stack Trace
"   at System.
Net.Mail.SmtpReplyReaderFactory.ProcessRead(Byte[] buffer, Int32 offset, Int32 read, Boolean readLine)\r\n   at System.
Net.Mail.SmtpReplyReaderFactory.ReadLines(SmtpReplyReader caller, Boolean oneLine)\r\n   at System.
Net.Mail.SmtpReplyReaderFactory.ReadLine(SmtpReplyReader caller)\r\n   at System.
Net.Mail.SmtpConnection.GetConnection(String host, Int32 port)\r\n   at System.
Net.Mail.SmtpTransport.GetConnection(String host, Int32 port)\r\n   at System.
Net.Mail.SmtpClient.GetConnection()\r\n   at System.
Net.Mail.SmtpClient.Send(MailMessage message)"
Outer Exception
System.
Net.Mail.SmtpException was unhandled
  Message="Failure sending mail."
  Source="System"
  StackTrace:
       at System.
Net.Mail.SmtpClient.Send(MailMessage message)
       at LabDemos.Mailer.test() in C:\Users\username\Documents\Visual Studio 2008\Projects\LabDemos\LabDemos\Mailer.cs:line 40
       at LabDemos.Program.Main(String[] args) in C:\Users\username\Documents\Visual Studio 2008\Projects\LabDemos\LabDemos\Program.cs:line 48
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       at System.AppDomain.nExecuteAssembly(Assembly assembly, String[] args)
       at System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel)
       at System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly()
       at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[] activationCustomData)
       at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext)
       at System.Activator.CreateInstance(ActivationContext activationContext)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: System.IO.IOException
       Message="Unable to read data from the transport connection: net_io_connectionclosed."
       Source="System"
       StackTrace:
            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(String host, Int32 port)
            at System.
Net.Mail.SmtpTransport.GetConnection(String host, Int32 port)
            at System.
Net.Mail.SmtpClient.GetConnection()
            at System.
Net.Mail.SmtpClient.Send(MailMessage message)
       InnerException: