Disruption in Communication: Microsoft Exchange Online Outage Halts IMAP4 Access to Mailboxes

Microsoft Working to Resolve Exchange Online Service Outage

Microsoft is currently addressing an Exchange Online service disruption that is causing intermittent issues for users trying to access their mailboxes via the Internet Mailbox Access Protocol 4 (IMAP4).

The incident, identified as EX1215307, was first reported on Wednesday at 23:35 UTC. Microsoft confirmed that other connection methods are unaffected and recommended affected users to retry accessing their emails.

According to Microsoft, a fix has been implemented to resolve the ongoing problems. The issue stemmed from a code conflict that led to an authentication misconfiguration.

Microsoft explained that a recent IMAP deployment caused an authentication support code conflict, resulting in a configuration issue that intermittently affects mailbox access for some users.

The company is currently in the process of deploying a configuration change to address the issue, with expectations of completion by the next scheduled update.

While specific regions and user numbers impacted by the IMAP4 access problem have not been disclosed by Microsoft, the incident has been flagged in the Microsoft 365 admin center as a critical service issue with noticeable user impact.

In November, Microsoft faced a similar Exchange Online outage that hindered customers’ access to mailboxes through the classic Outlook desktop client.

Earlier in October, Microsoft resolved an outage affecting access to Microsoft Teams, Exchange Online, and the admin center through Microsoft Entra single sign-on (SSO) authentication due to Multi-Factor Authentication (MFA) issues.

This week, Microsoft reversed its decision from April 2024 to enforce a daily limit of 2,000 external recipients on Exchange Online bulk email senders.

This is an ongoing story…

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