The Sentry team is making changes to increase the reliability of their service, which may require customer-side updates to firewall rules. The IP addresses associated with Sentry will be changing on December 1st, 2020, and organizations will need to update their applications to use a new organization subdomain IP address. This change aims to improve latency for applications sending events from outside North America by utilizing an event ingestion service behind an Anycast address. Organizations can find their subdomain by visiting the Sentry settings page and should reach out to support if they have any questions about the impact of this change on their service.