Common reasons why the device completely discards the push notification, causing it to never be delivered include:
- The device has power-saving mode enabled (this is common on some Android devices, and is enabled by default)
- The subscribed browser doesn’t have permission to use data in the background
- The user has changed their preferred browser (they’ll need to resubscribe to your push notifications on their new browser)
- The user has unsubscribed from push notifications (they can do this in many ways – we don’t know about it until the notification fails to deliver)
We’re able to detect some of the above areas and we mark the subscription as inactive when the platform tries to send to it, but there are also some cases that we’re unsure about. Please also remember that the longer your subscriber has been subscribed to your push project, the less likely they’re likely to still be active on the subscription (for all the above reasons). So your delivery rates may be accounting for these stale contacts.