In order to save resources, it'd be good to not send email notifications to inactive users.

The new notification system is already skipping notifications for suspended accounts:

https://github.com/3scale/porta/blob/7efaabdeec71877d74e580149890ef50c3ec1de5/app/workers/process_notification_event_worker.rb#L40-L43

However, the old system still send emails to everybody regardless their account state. After https://issues.redhat.com/browse/THREESCALE-11707, the old notification system is still going to be used for buyers, so it needs to be fixed.