In case you're wondering why your email has been quiet today - nationwide Outlook issue

Most of what I have left to do today is through Outlook. Our IT had no updates when they expect it to work again.

Sounds like a good excuse to leave a bit early.

same here

More than likely I am thinking the errors are cryptographic/certificate related, which would make sense if something in the authentication chain was failing validation. You'd basically start at the user request and trace it through authentication>> Exchange>> mailbox/transport, and see exactly where it starts falling apart.

From there I'd be looking at telemetry, authentication failure rates, exception logs, recent changes/deployments, and comparing a healthy environment against an affected one. That's how you start narrowing down whether you're dealing with a bad deployment, certificate/crypto issue, dependency failure, configuration problem, etc.

Same

I've sent two emails this afternoon that refuse to send. Good thing about the Draft folder ... I'll try again in the morning.