By Sergiu Gatlan
Publication Date: 2025-11-25 16:18:00
Microsoft is investigating an Exchange Online service outage that is preventing customers from accessing their mailboxes using the classic Outlook desktop client.
Microsoft first acknowledged the incident (tracked under EX1189820) at 09:57 AM UTC and, according to user reports on the DownDetector outage monitoring platform, it’s also causing server connection and login issues.
“Users may be unable to connect to their Exchange Online mailbox in the classic Outlook experience. We’re actively investigating the root cause of the connectivity failures,” Microsoft said.
“Impact is specific to users located in the Asia Pacific and North America regions attempting to connect to their Exchange Online mailbox using the classic Outlook experience.”
While Redmond has yet to share how many users are impacted by this ongoing issue, it has been tagged as an incident in the admin center, a label usually applied to service problems with significant user impact.
As a…
