Some users may intermittently be unable to access their mailboxes using Internet Mailbox Access Protocol 4 (IMAP4)

Title: Some users may intermittently be unable to access their mailboxes using Internet Mailbox Access Protocol 4 (IMAP4)

User impact: Users may intermittently be unable to access their mailboxes using IMAP4.

More info: Impact is specific to IMAP4, other connection methods are not impacted. Additionally, if users are actively facing this issue, retries may be successful.

Current status: We're continuing to deploy the configuration change and expect this process to complete by our next scheduled update.

Scope of impact: Some users that are attempting to access their mailboxes using IMAP4 may be intermittently impacted. This information may be updated as our investigation continues.

Root cause: A recent IMAP deployment related to authentication support contains a code conflict that introduced a configuration issue and is causing intermittent mailbox access issues for some impacted users.

Next update by: Thursday, January 8, 2026, at 1:30 PM UTC

Title: Some users may intermittently be unable to access their mailboxes using Internet Mailbox Access Protocol 4 (IMAP4)

User impact: Users may intermittently be unable to access their mailboxes using IMAP4.

More info: Impact is specific to IMAP4, other connection methods are not impacted. Additionally, if users are actively facing this issue, retries may be successful.

Current status: We've completed developing the configuration change and have validated it in our internal testing environment to ensure its efficacy in remediating impact. We've started deploying it to the impacted environments and we'll aim to provide a resolution timeline by our next scheduled update.

Scope of impact: Some users that are attempting to access their mailboxes using IMAP4 may be intermittently impacted. This information may be updated as our investigation continues.

Root cause: A recent IMAP deployment related to authentication support contains a code conflict that introduced a configuration issue and is causing intermittent mailbox access issues for some impacted users.

Next update by: Thursday, January 8, 2026, at 10:00 AM UTC

Title: Some users may intermittently be unable to access their mailboxes using Internet Mailbox Access Protocol 4 (IMAP4)

User impact: Users may intermittently be unable to access their mailboxes using IMAP4.

More info: Impact is specific to IMAP4, other connection methods are not impacted. Additionally, if users are actively facing this issue, retries may be successful.

Current status: We've identified a recent IMAP deployment related to authentication support contains a code conflict that introduced a configuration issue and is causing intermittent mailbox access issues for some impacted users. We're halting the deployment to prevent further impact from spreading and are developing a configuration change to restore service functionality. We'll aim to provide a resolution timeline once available.

Scope of impact: Some users that are attempting to access their mailboxes using IMAP4 may be intermittently impacted. This information may be updated as our investigation continues.

Root cause: A recent IMAP deployment related to authentication support contains a code conflict that introduced a configuration issue and is causing intermittent mailbox access issues for some impacted users.

Next update by: Thursday, January 8, 2026, at 6:30 AM UTC

Title: Some users may intermittently be unable to access their mailboxes using Internet Mailbox Access Protocol 4 (IMAP4)

User impact: Users may intermittently be unable to access their mailboxes using IMAP4.

Current status: We're investigating a potential issue with Exchange Online and checking for impact to your organization. We'll provide an update within 30 minutes.