SendMail 101 - How to send e-mails over SMTP (C# and ASP.NET)

/*-----------------------------------------------------------------------------------------------------------
 * Author           :Sujith John Thomas
 * Project          :SMTP Mail System Using ASP.NET 2.0
 * Module Name      :Send Mail
 * Dated            :16/07/2007
 * Modified on      :
 * ----------------------------------------------------------------------------------------------------------*/
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net;
using System.Net.Mail;

public partial class SendMail : System.Web.UI.Page
{
    #region DECLARATIONS
    private string _mMailServer;
    private string _mTo;
    private string _mFrom;
    private string _mMessage;
    private string _mSubject;
    private int _mPort;
    private MailMessage objMessage;
    #endregion
    #region EVENTS
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnSend_Click(object sender, EventArgs e)
    {
        Send();
    }
    protected void btnReset_Click(object sender, EventArgs e)
    {
        Clear();
    }
    #endregion
    #region METHODS
    //----------------------------------------------------------
    //Method to show the message 
    //----------------------------------------------------------
    private void Message(string strMessage)
    {
        Label lblMsg = new Label();
        lblMsg.Text = strMessage;
        phMessage.Controls.Add(lblMsg);
    }
    //----------------------------------------------------------
    //Method to send the mail.
    //----------------------------------------------------------
    private void Send()
    {    
        //Assigning value to the variables
        _mTo = txtTo.Text.Trim();
        _mFrom =txtFrom.Text.Trim();
        _mSubject = txtSubject.Text.Trim();
        _mMessage = txtBody.Text.Trim();

        //Getting the mail server ip from the web.config file
        _mMailServer = ConfigurationManager.AppSettings["MailServer"].ToString();
        //Getting the mail server port from the web.config file.
        _mPort = Int32.Parse(ConfigurationManager.AppSettings["MailServerPort"].ToString());

        try
        {   
            //Passing parameters to the Mail Message object.
            objMessage = new MailMessage(_mFrom, _mTo, _mSubject, _mMessage);
            //Instantiating Attachement object
            Attachment attach = new Attachment(fileAttach.PostedFile.FileName);
            //Adding attachment to the message.
            objMessage.Attachments.Add(attach);
            //Instantiating the SmtpClient
            SmtpClient objSmtpClient = new SmtpClient(_mMailServer, _mPort);
            //Setting default credentials to true
            objSmtpClient.UseDefaultCredentials = true;


            //Sending the mail. 
            objSmtpClient.Send(objMessage);
            Message("Mail has been sent successfully.");
            //Resetting the form
            Clear();
        }
        catch (FormatException ex)
        {

            Message("Format Exception:" + ex.Message);
        }
        catch (SmtpException ex)
        {

            Message("SMTP Exception:" + ex.Message);
        }
        catch (Exception ex)
        {

            Message("General Exception:" + ex.Message);

        }

    }
    //---------------------------------------------------------
    //Method for clearing the fields.
    //---------------------------------------------------------
    private void Clear()
    {
        txtTo.Text = string.Empty;
        txtFrom.Text = string.Empty;
        txtSubject.Text = string.Empty;
        txtBody.Text = string.Empty;
    }
    #endregion

}