gridview containing image via email not working in gmail

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C#

ASP.NET

I have to send a GridView containing an image column by email. The image displayed in the GridView is from a database so the image is stored there and not in a local folder. Now the problem is
The images are perfectly viewed in Yahoomail, but the image did not view with the Gmail.
How can I get this working?
My code as follows

private string getHTML(GridView gv)
   {

       this.Gridorderconfirmation.AllowPaging = false;
       this.Gridorderconfirmation.AllowSorting = false;
       this.Gridorderconfirmation.EditIndex = -1;

       this.GetselectedProductDetails();
       Gridorderconfirmation.Columns.RemoveAt(7);
       Gridorderconfirmation.DataBind();
       StringBuilder sb = new StringBuilder();
       StringWriter textwriter = new StringWriter(sb);
       HtmlTextWriter htmlwriter = new HtmlTextWriter(textwriter);
       Gridorderconfirmation.RenderControl(htmlwriter);
       htmlwriter.Flush();
       textwriter.Flush();
       htmlwriter.Dispose();
       textwriter.Dispose();
       return sb.ToString();
   }

  protected void Payimgbtn_Click(object sender, ImageClickEventArgs e)
  {
        try
           {
string emailGR = getHTML(Gridorderconfirmation);
MailMessage Msg = new MailMessage();
lblcomfirmationmail.Text = Session["Useremail"].ToString();
lblmailtotalcost.Text = Session["cost"].ToString();
lblusername.Text = Session["username"].ToString();
Msg.From = new MailAddress(lblcomfirmationmail.Text);
Msg.To.Add(lblcomfirmationmail.Text);
Msg.Subject = "Your Order Details";
Msg.Body = "Dear "+lblusername.Text +"" + emailGR + "  " + "Total Amout:" + "  " + lblmailtotalcost.Text + "<br/>";
Msg.IsBodyHtml = true;
Msg.BodyEncoding = Encoding.UTF8;
SmtpClient smtp = new SmtpClient();
smtp.Host = "smtp.gmail.com";
smtp.Port = 587;
smtp.Credentials = new System.Net.NetworkCredential("", "");
smtp.EnableSsl = true;
smtp.Send(Msg);
           }
           catch
           {
               string Msg = "<script>alert('Mail Sending Failed..try again!');</script>";
               ScriptManager.RegisterClientScriptBlock(this, typeof(Page), "alert", Msg, false);
               //Response.Write(@"<script language="'javascript'">alert('Mail Sending Failed..try again!')</script>");
           }
        this.Gridorderconfirmation.AllowPaging = true;
        this.Gridorderconfirmation.AllowSorting = true;
        this.Gridorderconfirmation.EditIndex = -1;
        this.GetselectedProductDetails();
}
}