How to send email to gmail using SMTPclient in C#?

I am using outloook 2003 and visual studio 2008. i want to develop an application that will send the email to any domain. but my code fails when i'm trying to send email to gmail, hotmail etc. actually all the messages is stored in C:\Inetpub\mailroot\Queue directory. Please help me how i send the email to gmail, hotmail a/c.

Thanks in Advance

Code is

System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
message.To.Add("sumitdawar@hotmail.com");
mess开发者_StackOverflowage.To.Add("sumitdawar@gmail.com");            
message.Subject = "This is sample mail";
message.From = new System.Net.Mail.MailAddress("Sumit.Dhingra@niit.com");
message.Body = "this is the message body";


System.Net.Mail.SmtpClient sss = new System.Net.Mail.SmtpClient("HO-KKJ-MAIL.in.niit.com");
sss.UseDefaultCredentials = false;
sss.DeliveryMethod = SmtpDeliveryMethod.PickupDirectoryFromIis;
sss.Credentials = new System.Net.NetworkCredential("Sumit.Dhingrar", "password","domain");

This is a good sample for Sending E-Mail with Gmail in C#

string from = me@gmail.com; //Replace this with your own correct Gmail Address

string to = you@gmail.com //Replace this with the Email Address to whom you want to send the mail

System.Net.Mail.MailMessage mail = new System.Net.Mail.MailMessage();
 mail.To.Add(to);
 mail.From = new MailAddress(from, "One Ghost" , System.Text.Encoding.UTF8);
mail.Subject = "This is a test mail" ;
mail.SubjectEncoding = System.Text.Encoding.UTF8;
mail.Body = "This is Email Body Text";
mail.BodyEncoding = System.Text.Encoding.UTF8;
mail.IsBodyHtml = true ;
mail.Priority = MailPriority.High;

SmtpClient client = new SmtpClient();
//Add the Creddentials- use your own email id and password

 client.Credentials = new System.Net.NetworkCredential(from, "Password");

client.Port = 587; // Gmail works on this port
client.Host = "smtp.gmail.com";
client.EnableSsl = true; //Gmail works on Server Secured Layer
       try
        {
            client.Send(mail);
        }
        catch (Exception ex) 
        {
            Exception ex2 = ex;
            string errorMessage = string.Empty; 
            while (ex2 != null)
            {
                errorMessage += ex2.ToString();
                ex2 = ex2.InnerException;
            }
   HttpContext.Current.Response.Write(errorMessage );
        } // end try 

Are you sure

message.From = new System.Net.Mail.MailAddress("Sumit.Dhingra@niit.com");

is right? Does this method have an overload like this?