Oops, they did it again: Microsoft breaks Outlook with another dubious update

Users of Microsoft's email service might be feeling a distinct sense of déjà vu after the web version of Outlook last night blocked access to Exchange Online mailboxes.

According to Microsoft, the problem was due to "a recent change made to a portion of Outlook on the web infrastructure, that may have resulted in impact."

Reverting the change did the trick, and service was restored, but the question must be asked - does Microsoft test its changes before deploying to production?

The problems, according to DownDetector, began around 1730 UTC on March 19 and appeared to be worldwide. The company admitted to them via social media shortly after, saying: "We're investigating reports of an issue affecting users' ability to access Outlook on the web."

Half an hour later, the company admitted it made a change that might be responsible. That change was reverted, and services started returning to normal.

This sort of incident is becoming depressingly commonplace. A lengthy outage occurred at the beginning of March which Microsoft also blamed on some dodgy code.

Enterprise administrators are the ones truly suffering. Yes, users are finding email access suddenly blocked, yet it is the administrator who is on the front line. If the company has gone all-in on Microsoft's cloud email services, that poor admin can do little more than place a support call and raise a ticket with the cloud provider.

The issue also highlights the complexity and scale of cloud services, where one wrong move by an engineer can result in an outage for tens of thousands of customers. The only way to mitigate this is through rigorous testing and a thorough understanding of the change's implications.

The Register asked Microsoft how it validates its changes and what assurance it could give customers that this issue won't be repeated. The company is yet to respond. ®