Microsoft Exchange Online has recorded an outage which affected users all over the world, causing disruptions and preventing access to email for several hours. Many emails sent to Exchange Online mailboxes did not reach their intended recipients.
Users who are affected see “550 5.4.1 Rejected recipient address: Access is denied “Beginning today at 1:11 PM UTC, errors occurred when attempting to send or receive messages. Microsoft then stated that it had discovered a potential Directory Based Edge Blocking (DBEB) issue and is looking into it further. Administrators can use DBEB to reject messages sent to invalid recipients in Exchange Online.
Microsoft’s engineering team began investigating the issue as soon as it was reported, and the company later confirmed that it affected users worldwide. Microsoft apologized for the inconvenience and continued to provide updates on the situation on a regular basis.
“We’re investigating an issue wherein users may be unable to access their Exchange Online mailboxes via any connection method. Additional details can be found within the Service Health Dashboard under EX522020,” Microsoft tweeted earlier today.
The company said that “impact is specific to users who are served through the affected infrastructure in North America, Europe, and the United Kingdom.” As of approximately 3 PM ET, Microsoft tweeted that it is now routing traffic away from what appears to be the affected infrastructure as a potential mitigation strategy.
The sources for this piece include an article in BleepingComputer.