Opting-in to receive push notifications is different from email subscription.
The contact (i.e. the app users) is fully in charge, as they can enable and disable notifications for any app they have installed on their device.
This is done at operating system (OS) level, and the Ometria SDK checks the settings every time the contact opens the app on their device.
When we don't have an up to date opt-in status
This can happen for lots of reasons, e.g. if the contact disables their notifications without opening the app then Ometria won't receive the data and won't record that contact as having 'opted-out'.
You don't need to worry about sending notifications to these contacts, as if they have disabled their app notifications there can be no breach of rules - the operating system itself has the correct settings, and the contact simply won't receive any notifications even if you send them.
By default, our automation triggers only enter contacts into campaigns if they are opted-in for email, though there is an option to include all contacts (see: Ignore email opt-in for automation campaigns).