How to direct email page and return?

When a site visitor is viewing page1.htm (for example), they will find a link for sending the webmaster (me) an email. When they click that link they are taken to page emailform.php and fill out the fields for return email, subject, and body. When clicking submit, the html opens page emailsend.php which sends the email.

Question: How can I automatically direct the user back to page1.html, or page2.html or what ever page where they clicked the email link.

Is there an HTML variable that I can grab that tells me the previous page?
If so, can I put the value of that variable somewhere such that the PHP script or the code in the next html page can get it and use it?

Thanks for your time guys.