Email only Checked row from GridView using ASP.Net

Below is the JQuery for Check / Uncheck

<script type="text/javascript">

        $(document).ready(function () {

            $('[id$=chkHeader]').click(function () {

                $("[id$='chkChild']").attr('checked', this.checked);

            });

        });

    </script>

And the Html code is

<asp:GridView ID="grdSearch" runat="server" AllowPaging="True" Width="700px"

                    AutoGenerateColumns="False" BackColor="White" BorderColor="Aqua"

                    DataKeyNames="MemberNO" Style="margin-top: 0px"

                    onpageindexchanging="grdSearch_PageIndexChanging">

                    <PagerSettings FirstPageText="First" LastPageText="Last" NextPageText="Next" PreviousPageText="Previous" Position="TopAndBottom" Mode="NextPreviousFirstLast" />

                    <HeaderStyle BackColor="#003399" Font-Bold="True" ForeColor="#CCCCFF" />

                    <PagerStyle BorderColor="#00CCFF" HorizontalAlign="Center" />

                    <Columns>

                        <asp:TemplateField>

                            <HeaderTemplate>

                                <asp:CheckBox ID="chkHeader" runat="server" />

                            </HeaderTemplate>

                            <ItemTemplate>

                                <asp:CheckBox ID="chkChild" runat="server" />

                            </ItemTemplate>

                        </asp:TemplateField>

                        <asp:BoundField DataField="customerid" HeaderText="Customer id" SortExpression="customerid" />

                        <asp:BoundField DataField="customername" HeaderText="Customer name" ItemStyle-HorizontalAlign="Left"

                            SortExpression="customername">

                            <ItemStyle HorizontalAlign="Left" />

                        </asp:BoundField>

                        <asp:BoundField DataField="Email" HeaderText="Email" SortExpression="Email" />

                        </Columns>

                </asp:GridView>

 

protected void Button1_Click(object sender, EventArgs e)

    {

        foreach (GridViewRow gr in grdSearch.Rows)

        {

            CheckBox chkEmail = ((CheckBox)gr.Cells[0].FindControl("ChkEmailSelection"));

            if (chkEmail.Checked == true)

            {

                var fromAddress = new MailAddress("username@domainname.com", "Admin");

                var toAddress = new MailAddress(gr.Cells[0].Text);

                const string fromPassword = "xxxxxx";

                string subject = Yoursubject.Text;

                string body = YourMessage.Text;

                var smtp = new SmtpClient

                {

                    Host = "smtp.yourdomainname.com",

                    Port = 587,

                    EnableSsl = true,

                    DeliveryMethod = SmtpDeliveryMethod.Network,

                    UseDefaultCredentials = false,

                    Credentials = new NetworkCredential(fromAddress.Address, fromPassword)

                };

                using (var message = new MailMessage(fromAddress, toAddress)

                {

                    Subject = subject,

                    Body = body

                })

                {

                    smtp.Send(message);

                }

            }

        }

    }