public bool ValidEmailAddress(string emailAddress)
        {
            // Confirm that the email address is not empty.
            if (emailAddress.Length == 0)
            {
                MessageBox.Show("Please, enter your email");
                return false;
            }

            // Confirm that there is an "@" and a "." in the email address, and in the correct order.
            if (emailAddress.IndexOf("@") > -1)
            {
                if (emailAddress.IndexOf(".", emailAddress.IndexOf("@")) > emailAddress.IndexOf("@"))
                    return true;
            }
                MessageBox.Show("Invalid input format of email! "+
                              "Example: 'someone@example.com' ");
                return false;


        }