Microsoft is working to address an ongoing Exchange Online outage that is preventing customers from accessing their mailboxes and calendars.

“We’re investigating reports of some users experiencing issues when accessing their Exchange Online mailbox via one or more connection methods,” Microsoft said when it acknowledged the issue at 06:42 AM UTC.

As Microsoft explained in a Microsoft 365 admin center update under EX1253275, Outlook on the web, Outlook desktop, Exchange ActiveSync, and other Exchange Online connection protocols are all affected by this outage.