Export GridView to Excel and send Excel File as email attachment in ASP.Net

This way

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="CustomerId" HeaderText="Customer Id" ItemStyle-Width="80" />
        <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="120" />
        <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="120" />
    </Columns>
</asp:GridView>
<br />
<asp:Button Text="Export" OnClick="ExportExcel" runat="server" />

Namespaces

using System.IO;
using System.Data;
using ClosedXML.Excel;
using System.Net.Mail;
using System.Configuration;
using System.Data.SqlClient;

Code

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        GridView1.DataSource = this.GetData();
        GridView1.DataBind();
    }
}

private DataTable GetData()
{
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT * FROM Customers"))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataTable dt = new DataTable())
                {
                    sda.Fill(dt);
                    return dt;
                }
            }
        }
    }
}

protected void ExportExcel(object sender, EventArgs e)
{
    //Get the GridView Data from database.
    DataTable dt = GetData();

    //Set DataTable Name which will be the name of Excel Sheet.
    dt.TableName = "GridView_Data";

    //Create a New Workbook.
    using (XLWorkbook wb = new XLWorkbook())
    {
        //Add the DataTable as Excel Worksheet.
        wb.Worksheets.Add(dt);

        using (MemoryStream memoryStream = new MemoryStream())
        {
            //Save the Excel Workbook to MemoryStream.
            wb.SaveAs(memoryStream);

            //Convert MemoryStream to Byte array.
            byte[] bytes = memoryStream.ToArray();
            memoryStream.Close();

            //Send Email with Excel attachment.
            using (MailMessage mm = new MailMessage("sender@gmail.com", "recipient@gmail.com"))
            {
                mm.Subject = "GridView Exported Excel";
                mm.Body = "GridView Exported Excel Attachment";

                //Add Byte array as Attachment.
                mm.Attachments.Add(new Attachment(new MemoryStream(bytes), "GridView.xlsx"));
                mm.IsBodyHtml = true;
                SmtpClient smtp = new SmtpClient();
                smtp.Host = "smtp.gmail.com";
                smtp.EnableSsl = true;
                System.Net.NetworkCredential credentials = new System.Net.NetworkCredential();
                credentials.UserName = "sender@gmail.com";
                credentials.Password = "<password>";
                smtp.UseDefaultCredentials = true;
                smtp.Credentials = credentials;
                smtp.Port = 587;
                smtp.Send(mm);
            }
        }
    }
}

Screenshot