- Have a user unsubscribe to a notification (Incident commented, for instance)
- Have the notification use an email template, which will in turn use an email script
- Have this email script send the notification to the recently created user in Cc
- Impersonate that user and comment an incident (or do any action that should (not) trigger the associated notification)
- You will see that the user who unsubscribed to the notification will receive that notification anyway
This is due to the fact that the mail script is externally inserting the email address. This is similar to adding the recipient externally with a BR and it is done outside the checks performed by notification engine. Therefore the notification engine would not be able to see if the additional recipient has a filter or not.
It is therefore expected behaviour and it should be taken into account while designing email notifications.