'Page Expired' message when a user uses their browser's 'back' button?

[Jack.Straw]

Hi.  Is there a way to give people a 'page expired' message if they use the 'Back' button on their browser?  Here's the scenario:

[list]
[*]User fills out a form and submits it.
[*]On submittal the browser uses CGIemail to email the form contents back to the user.
[*]The CGIemail 'success' value instructs the browser to load a custom success page, where a hidden form with hidden values is auto-submitted, using CGIemail again to send another email to an administrator.
[*]The CGIemail 'success' value from the 2nd 'hidden' form instructs the browser to load the real success page, where the user is notified that the process was a success.
[/list]

This all works great.  When the user submits the form an email is sent to their email address, and then another email containing different information is sent to an administrator.  However, if the user tries to use the 'back' button on their browser from the final success page, a duplicate email gets sent.  How could i prevent this?

Thanks in advance of any advice you can offer!
-Jack

[taith]

no... when the press "back", it loads the file from cache, you can do it if you have cache set off... by on the new page set a session var, then on your form page, detect for it...