C# windows application to send emails

Hi Experts,
I require C# windows application to send email with attachment. I got the error  like
ex.Message      "Could not access 'CDO.Message' object."
ex.InnerException.Message    "Exception has been thrown by the target of an invocation."      
ex.InnerException.InnerException.Message   "The transport failed to connect to the server.\r\n". Please help.
I am using Visual studio 2005, C#, backend is sql2005, Win xp

Entire Error message is
"Exception Occured: System.Web.HttpException: Could not access 'CDO.Message' object. ---> System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Runtime.InteropServices.COMException (0x80040213): The transport failed to connect to the server. --- End of inner exception stack trace --- at System.RuntimeType.InvokeDispMethod(String name, BindingFlags invokeAttr, Object target, Object[] args, Boolean[] byrefModifiers, Int32 culture, String[] namedParameters) at System.RuntimeType.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParameters) at System.Type.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args) at System.Web.Mail.LateBoundAccessHelper.CallMethod(Type type, Object obj, String methodName, Object[] args) at System.Web.Mail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) --- End of inner exception stack trace --- at System.Web.Mail.LateBoundAccessHelper.CallMethod(Object obj, String methodName, Object[] args) at System.Web.Mail.CdoSysHelper.Send(MailMessage message) at System.Web.Mail.SmtpMail.Send(MailMessage message) at TestingWeb1.Email_P2.btnSubmit_Click(Object sender, EventArgs e) in c:\inetpub\wwwroot\testingweb1\email_p2.aspx.cs:line 75Your E-mail has been sent sucessfully "

Please help.

Advance Thanks,
SureshStart Free Trial