[QF]caused rules

i have 2 fields (there are more than 2, but unnessesary for this question) in my form the first is an emailfield and the second is a radiobutton group called "do you want to get a newsletter?" -> yes/no my problem is that if a user dont want to get a newsletter the email should not be required i do it the similar way like the code below: function checkPerMailAndEmail($values){ if(strlen($values["email"])<2 && $values["newsletter_per_post"]==0) $GLOBALS["langStr"][LANG]['rules_email_2']; return empty($errors)? true: $errors; } but is there another way to do that?