Sending mail through ASP.NET with C# not working

Question

I am trying to send a keycode to the student through email but it is not sending . Whenever I click on submit button to send the keycode it showed me the message := "At least one of the From or Sender fields is required, and neither was found." but I have already included it in my code.

 

HERE IS MY .cs FILE :

 

 

using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Xml.Linq;

using System.Web.Mail;

using System.Web.Util;

public partial class admin_ExamSchedule : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

int examtypeid = Convert.ToInt32(Session["examtypeid"].ToString());

ddlExamIdNotAttempted.DataSource = objAttemptexam.getNotAttemptedExamId(examtypeid);

ddlExamIdNotAttempted.DataValueField = "ExamId";

ddlExamIdNotAttempted.DataTextField = "ExamName";

ddlExamIdNotAttempted.DataBind();

// Response.Write("<script>alert('Must Select Any One')</script>");

//ddlExamIdAttempted.DataSource = objAttemptexam.getAttemptedExamId();

//ddlExamIdAttempted.DataValueField = "ExamId";

//ddlExamIdAttempted.DataTextField = "ExamName";

//ddlExamIdAttempted.DataBind();

}

}

BALexam objAttemptexam = new BALexam();

protected void btnSubmit_Click(object sender, EventArgs e)

{

try

{

objAttemptexam.uid = Convert.ToInt32(Session["uid"].ToString());

objAttemptexam.ExamReqDate = Convert.ToDateTime(Session["preferdate"]).ToString();

objAttemptexam.ExamAssignDate =txtAssignExamDate.Text;

objAttemptexam.ExamId = Convert.ToInt32(ddlExamIdNotAttempted.SelectedValue);

objAttemptexam.ExamRequestId = Convert.ToInt32(Session["ExamRequestId"].ToString());

// objAttemptexam.UserName = Session["User"].ToString();

objAttemptexam.KeyCode = txtKeyCode.Text;

string strMsg;

SendMails();

int i = objAttemptexam.InsertScheduleExam(out strMsg);

if (i > 1)

{

ClearData();

LblMsg.Text = strMsg;

}

else

LblMsg.Text = strMsg;

}

catch (Exception ex)

{

LblMsg.Text = ex.Message;

}

}

void SendMails()

{

MailMessage objMail = new MailMessage();

objMail.From = "OnLineWebExamination.Com";

objMail.To = "Localhost";

objMail.Subject = "OnLineExam Schedule.";

objMail.Body = "Your Key : " + txtKeyCode.Text + "" + "\n" +

"Your ExamId : " + Convert.ToInt32(ddlExamIdNotAttempted.SelectedValue) + "" + "\n" +

"Your ExamDate : " + txtAssignExamDate.Text;

SmtpMail.SmtpServer = "LocalHost";

SmtpMail.Send(objMail);

Page.RegisterClientScriptBlock("Dhanush", "<script>alert('Key Send to Student Successfully...')</script>");

}

private void ClearData()

{

txtAssignExamDate.Text = txtKeyCode.Text = "";

}

protected void ddlExamIdAttempted_DataBound(object sender, EventArgs e)

{

ddlExamIdNotAttempted.Items.Insert(0, "--Select--");

}

protected void ddlExamIdNotAttempted_SelectedIndexChanged(object sender, EventArgs e)

{

}

protected void LB_Click(object sender, EventArgs e)

{

Response.Redirect("frmShowExamRequest.aspx");

}

}

 

HERE IS MY .aspx file :

 

<%@ Page Language="C#" MasterPageFile="~/admin/AdminMasterPage.master" AutoEventWireup="true" CodeFile="~/admin/frmExamSchedule.aspx.cs" Inherits="admin_ExamSchedule" Title="Untitled Page" %>

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentBody" Runat="Server">

<center>

<table border="2">

<tr><td style="font-size: x-large" colspan="3">Exam Schedule</td></tr>

<tr><td >ExamId</td><td><asp:DropDownList ID="ddlExamIdNotAttempted" runat="server" Width="150"

onselectedindexchanged="ddlExamIdNotAttempted_SelectedIndexChanged"></asp:DropDownList></td>

<%-- <td><asp:DropDownList ID="ddlExamIdAttempted" runat="server" Width="150"

ondatabound="ddlExamIdAttempted_DataBound"></asp:DropDownList></td>--%>

</tr>

<tr><td >Date Of Assign</td>

<td><asp:TextBox ID="txtAssignExamDate" runat ="server" Width="150px" ></asp:TextBox>

&nbsp;&nbsp;

<cc1:CalendarExtender ID="CE1" runat="server" TargetControlID="txtAssignExamDate">

</cc1:CalendarExtender></tr>

<tr><td >Key Code</td><td><asp:TextBox ID="txtKeyCode" runat="server" Width="150"></asp:TextBox></td></tr>

<tr><td colspan="2">

<asp:Button ID="btnSubmit" runat="server" Text="Submit"

onclick="btnSubmit_Click" Height="31px" />&nbsp;</td></tr>

</table>

<asp:Label ID="LblMsg" runat="server" Text=""></asp:Label>

&nbsp;

<asp:LinkButton ID="LBScheduleExam" runat="server" onclick="LB_Click">Go To

Schedule Exam</asp:LinkButton>

</center>

</asp:Content>