Fatal error: Uncaught Error: Class "google\appengine\api\mail\Message" not found in /home/ondemand/test.ondemandpro.net/php-docs-samples/appengine/php55/mail/index.php:29 Stack trace: #0 {main} thrown in /home/ondemand/test.ondemandpro.net/php-docs-samples/appengine/php55/mail/index.php on line 29