Between approximately 2:03 PM and 3:51 PM US Pacific time on 20 August, deliveries on our US site that included message center messages may have been delayed over an hour. Customers may have also noticed increased 5xx errors on message center APIs between 1:03PM and 2:42PM, during which end users may not have been able to view their message center messages. This was due to a performance issue related to a spike in traffic. Our Engineering team is working on a long-term solution for this issue to prevent recurrences. We apologize for any inconvenience.