Microsoft Exchange Outage Leaves Users Without IMAP Email Access

As reported by BleepingComputer, Microsoft Exchange Online is currently experiencing a service outage that intermittently blocks mailbox access over IMAP4 (Internet Mailbox Access Protocol 4).

Microsoft confirmed the issue under incident EX1215307, which the company first acknowledged on January 7, 2026, at 23:35 UTC. According to Microsoft, the problem affects IMAP connections only, while other access methods, such as Outlook on the web and alternative protocols, continue to work normally.

What’s causing the IMAP outage

Microsoft traced the issue to a code conflict introduced during a recent IMAP deployment. That change triggered an authentication misconfiguration, which now prevents some users from connecting to their mailboxes through IMAP-based email clients.

Microsoft has already deployed an initial fix and is actively rolling out a configuration update to fully resolve the problem. In the meantime, the company says retrying the connection may temporarily restore access for some users.

Impact and current status

Microsoft has not disclosed which regions are affected or how many users experience the issue. However, the company has classified the outage as a critical incident in the Microsoft 365 admin center, which signals a high-impact service disruption.

Other Exchange Online services remain operational, and Microsoft continues to monitor the rollout of the corrective changes.

A string of recent Exchange Online issues

This IMAP outage follows several recent Exchange Online-related problems. Microsoft has already announced plans to drop support for Legacy Mobile Email, urging organizations to update affected clients. At the same time, a recent Outlook Classic update has reportedly caused issues with encrypted emails, further frustrating administrators and users.

Are you affected by the Exchange Online IMAP outage? Share your experience in the comments below.