Fixed error that has been in the code for 2 years. Prior to updating to ...

...the new email API the code used $return variable to indicate whether sending the e-mail was successful. After the API was updated the return variable was renamed to $success, but the code still returned (now undefined) $return variable. Naming the variable to $success is better because it conveys the intent of the data, so the remaining $return variable was renamed to $success.