Title: Some users’ encrypted email messages sent from a shared mailbox to external domains may fail to send in Exchange Online
User impact: Users’ encrypted email messages sent from a shared mailbox to external domains may fail to send in Exchange Online.
Current status: We’ve completed applying our additional optimizations, and service health telemetry indicates the issue is resolved. We’re reaching out to a subset of affected users to further confirm that users are no longer seeing impact and that the issue is resolved for all users.
Scope of impact: This issue impacts some users’ encrypted email messages sent from a shared mailbox to external domains in Exchange Online.
Start time: Tuesday, March 12, 2024, at 6:17 AM UTC
Root cause: A recent change, which was intended to enable the service to perform rule evaluation at the component level, rather than at the email message level, has increased the amount of requests to the service responsible for providing the license to encrypt or decrypt messages, resulting in our traffic management systems to be initialized and failing these requests to the service.
Next update by: Friday, March 15, 2024, at 8:30 PM UTC
