Override the Contact Us page?

I googled but can't find the answer.

I want to override the Contact Us page, so that email title, instead of default "Message from Store name", I want something like "Message from Store name by customer name".

I figured the file should be includes\modules\pages\contact_us\header_php.php, and I changed the line 63 to be something like:

zen_mail($send_to_name, $send_to_email, EMAIL_SUBJECT . ' by ' . $name, $text_message, $name, $email_address, $html_msg,'contact_us');

But it does not work. And looks like the system is not even reading this file.

Any idea of it?

Thanks.

As a matter of fact, problem solved.
The file is the correct one.
Somehow I found, if I rename the old one, instead of delete it, somehow the system is still using the old file. Kind of strange.