Email subscribers are moved into the "Quarantined" tab when we try to deliver mail to them but encounter a permanent failure. Sometimes this is due to them marking us as spam, or we have other troubles delivering the email due to aggressively configured mail servers.
SMS subscribers are moved into the "Quarantined" tab when we try to deliver an SMS to them but encounter a permanent failure (such as the phone number being disconnected or invalid).
Webhook subscribers are quarantined after we have made 10 failed HTTP requests to the subscriber's endpoint over the course of approximately an hour. We consider a request to have failed if the endpoint does not respond with a 2xx status code within 30 seconds of us making the HTTP request. On the 10th failed attempt, we will move them to "quarantined" and send an email to the email address we have recorded for that webhook subscriber notifying them of this action.
Quarantined subscribers will not receive any future notifications from us. If a subscriber has not been reactivated within 90 days of being quarantined, they will be automatically purged (permanently removed).
If a subscriber has been quarantined or purged, end users can re-subscribe to a StatusPage to reactivate themselves and receive incident notifications again for that page.
Quarantined subscribers do not count towards the page's total subscriber allocation limit.
You can reactivate subscribers, or you can unsubscribe them completely. You can reactivate or unsubscribe on an individual basis, or through bulk actions.
Reactivating a subscriber will move them back into the Active Subscribers list. You may want to do this if the subscriber is a valid subscriber.
Unsubscribing a subscriber will completely remove (purge) them from the system. You may want to do this if the email is not a valid email address.