Forms and Results with PHP

I have a form that a user can put his contact info. This form posts to a file called results.php. The results.php file has a mail() command and the echo (i.e. <? echo "$name"; ?>) to show the user confirmation of what he has submitted. However, if someone goes directly to results.php it will show Name: blank and email blank information. Is there a way for the page to post an error stating no information was submitted or is there a way to enable the page to process without information? Thanks for the help, Ben