When you apply universal email to a page, there are a couple of require once lines that get added to attach helper files:
<?php require_once("webassist/email/mail_php.php"); ?>
<?php require_once("webassist/email/mailformatting_php.php"); ?>
these are missing in your serveareas.php page. Add those 2 lines at line 1 of your page, you may need to adjust the paths.