hi

try this

SmtpClient stc = new SmtpClient();
        stc.Host = System.Configuration.ConfigurationSettings.AppSettings.Get("smtpserver").ToString();
        stc.Timeout = Convert.ToInt32(System.Configuration.ConfigurationSettings.AppSettings.Get("smtpconnectiontimeout").ToString());
        stc.Port = Convert.ToInt32(System.Configuration.ConfigurationSettings.AppSettings.Get("smtpserverport").ToString());
        stc.Credentials = new System.Net.NetworkCredential( System.Configuration.ConfigurationSettings.AppSettings.Get("sendusername").ToString(), System.Configuration.ConfigurationSettings.AppSettings.Get("sendpassword").ToString());
        stc.DeliveryMethod = Convert.ToInt32(System.Configuration.ConfigurationSettings.AppSettings.Get("sendusing").ToString());
        

        MailMessage mm = new MailMessage();
        mm.From = System.Configuration.ConfigurationSettings.AppSettings.Get("sendusername").ToString(); ;
        mm.To = System.Configuration.ConfigurationSettings.AppSettings.Get("emailto").ToString();
        mm.Subject = "Enquiry Email from Web Visitor";
        mm.IsBodyHtml = true;
        mm.Body = strEmailText;


        stc.Send(mm);