Workers trying to log in to Microsoft Outlook experienced unexpected problems Monday morning, with some users receiving error messages and unexpected signouts.

Microsoft confirmed that an April 27 “service degradation” incident, commonly known as an outage to us mere mortals, left some users around the world unable to access their Outlook.com email.

Users "may experience intermittent issues signing in to Outlook.com", the company says, as well as possibly seeing an "experience intermittent sign‑in failures, including “too many requests” errors or...