while (1) {
		$sth = $dbh->prepare(qq{select * from customers where mark=0});
		$sth->execute() or die "$DBI::errstr\n";
		while ($sth->fetch) {
			my $content = construct_the_customers_template();
			send_customer_mail($coutnet);
			mark_the_flag_in_msgdb();  # set the mark field to 1 ,represent has sent!
		}
	}