Error messages galore from contact.php and mailing.php, but eveything works? Should I worry? how do I fix it?
To suppress these messages, add the following code to your settings.php or civicrm.settings.php

ini_set('error_reporting', E_ALL &amp; ~E_DEPRECATED &amp; ~E_NOTICE);


Long answer on Drupal Answers.

CiviCRM generates a substantial number of E_NOTICE messages - these are notices, which is less severe than warnings. If they bother you, submitting patches to address them is a great way to start contributing code to CiviCRM!