protected void btn_send_Click(object sender, EventArgs e)
        {
            string msg = txt_send.Text;

            MembershipUser CurrentUser = Membership.GetUser();
            Guid           senderId    = (Guid)CurrentUser.ProviderUserKey;
            Guid           receiverId  = new Guid(ddl_users.SelectedValue);
            string         message     = txt_send.Text;
            string         date        = DateTime.Now.ToString("yyyy-MM-dd");

            MessageBLL.AddMsg(senderId, receiverId, message, date);
            Response.Redirect($"~/Pages/Users/Message.aspx?messaging={receiverId}");
        }