<form action="" name="form1" method="POST" accept-charset="UTF-8">
<input type="checkbox" name="checkbox_1" value="1">
<input type="text" name="e_mail" />
<input type="submit" name="submit" value="Submit" />
</form>
<?php
if(isset($_POST['e_mail'])){
echo "$e_mail";
}
?>
php will throw an error the way you have it. Also, you would only need 2 forms if you are going to have them process differently.