Emailing BI Publisher Reports to External Users

Has anyone successfully enabled BI Publisher output to email to external users? I have reviewed documentation in PeopleBooks related to this topic. I have created a custom app package and class to populate an array of email addresses as described in PeopleBooks, and I've added the custom package to the psxp_ext_email_appclass property in the Report Definition Properties tab. However, my custom code is never called to retrieve the addresses. Thanks.