Sending Mail in Asp.net

 For sending a mail in Asp.net,import System.Net.Mail Namespace.This is a simple application which u can use as a feedback form or contact us page.

Create a simple default.aspx page with following code.
<form id="form1" runat="server">
 
  <div style="text-align: center">
  <div>
  <asp:Label ID="lblErrorMsg" runat="server" Text="LPublish Postabel"></asp:Label>

  </div>
  <table border="1">
  <tr>
  <td colspan="2" style="font-weight: 700; text-align: center; background-color: #F7C331;">
  Send Mail in ASP.net through SMTP
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700; text-align: right;">
  TO
  </td>
  <td>
  <asp:TextBox ID="txtTo" runat="server" Width="242px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700; text-align: right;">
  From
  </td>
  <td>
  <asp:TextBox ID="txtFrom" runat="server" Width="242px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700; text-align: right;">
  CC
  </td>
  <td>
  <asp:TextBox ID="txtcc" runat="server" Width="242px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700; text-align: right;">
  BCC
  </td>
  <td>
  <asp:TextBox ID="txtbcc" runat="server" Width="242px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700; text-align: right;">
  Subject
  </td>
  <td>
  <asp:TextBox ID="txtSub" runat="server" Width="242px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700; text-align: right;">
  Message
  </td>
  <td>
  <asp:TextBox ID="txtMsg" runat="server" TextMode="MultiLine" Height="75px" Width="246px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td style="font-weight: 700">
  Attachment
  </td>
  <td>
  <asp:FileUpload ID="FileUpload1" runat="server" Width="244px" />
  </td>
  </tr>
  <tr>
  <td>
 
  </td>
  <td>
  <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="SendMail" />
  </td>
  </tr>
  </table>
  </div>
  </form>
And paste the code in Default.aspx.cs page(i,e codebehind )
try
  {
  SmtpClient stp = new SmtpClient();
//Create a smtpclient object for sending mail.
  MailMessage mail = new MailMessage();
//Create a MailMessage object for drafting mail.
  MailAddress madd = new MailAddress(txtFrom.Text);
  mail.From = madd;
  mail.To.Add(txtTo.Text);

  if (!string.IsNullOrEmpty(txtcc.Text.Trim()))
  {
  mail.CC.Add(txtcc.Text.Trim());
  }
  if (!string.IsNullOrEmpty(txtbcc.Text.Trim()))
  {
  mail.CC.Add(txtbcc.Text.Trim());
  }

  if (FileUpload1.HasFile == true)
  {
  string attachFile = FileUpload1.PostedFile.FileName.ToString();
  mail.Attachments.Add(new Attachment(attachFile));
  }

  mail.Subject = txtSub.Text.Trim();
  mail.Body = txtMsg.Text.Trim();


  stp.Send(mail);//sending mail using Send method of SmtpClient class.
  lblErrorMsg.Text = "Mail successfully sent.";
  }
  catch (Exception ex)
  {
  lblErrorMsg.Text = ex.Message;
  }

Mail Setting in Web.Config file.
Using this code under the configuration tag
<system.net>
  <mailSettings>
  <smtp deliveryMethod="Network" from="jitendra@infotechsolution.com" >
  <network defaultCredentials="true" host="192.168.0.1" port="25" userName=" jitendra@infotechsolution.com " password="test"/>

  </smtp>
  </mailSettings>
 </system.net>

Accssing web.config setting in our code behind page
First import System.Configuration Namespace.
Configuration conf = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration(HttpContext.Current.Request.ApplicationPath);
  System.Net.Configuration.MailSettingsSectionGroup mailsettings = (System.Net.Configuration.MailSettingsSectionGroup)conf.GetSectionGroup("system.net/mailSettings");
  Response.Write("DefaultCredentials:->" + mailsettings.Smtp.Network.DefaultCredentials);
  Response.Write("
Host:->" + mailsettings.Smtp.Network.Host);
  Response.Write("
Port:->" + mailsettings.Smtp.Network.Port);
  Response.Write("
UserName:->" + mailsettings.Smtp.Network.UserName);
  Response.Write("
Password:->" + mailsettings.Smtp.Network.Password);