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Microsoft has confirmed that the January 13, 2026 cumulative update for Windows 11, KB5074109 (OS builds 26100.7623 and 26200.7623), can cause classic Outlook POP account profiles to hang, freeze, or fail to exit properly, leaving users unable to restart Outlook or reliably save sent messages.
Microsoft shipped KB5074109 as the January 2026 security and quality rollup for Windows 11. The update was intended to address multiple issues—including a fix for devices with Neural Processing Units (NPUs) that were consuming power while idle and changes to Secure Boot certificate deployment—but it has also been linked to a set of regressions affecting several areas of Windows client functionality. Administrators and users reported problems ranging from Remote Desktop credential prompts to application hangs; within days Microsoft added a formal support notice for the Outlook POP issue and opened investigations. KB5074109 covers both Windows 11 version 24H2 and 25H2, and installs as OS builds 26100.7623 (24H2) and 26200.7623 (25H2). The Outlook-specific support advisory was posted and updated by Microsoft on January 15, 2026; their guidance identifies the problem as emerging and notes that Outlook and Windows teams are actively investigating.
Actionable takeaways:
Outlook users and administrators should monitor Microsoft’s support pages and the Microsoft Learn forums for updates; prepare rollback procedures for critical workstations; and test any remedial steps in a controlled environment before applying them broadly. The coming days are likely to reveal either a KIR deployment or an OOB hotfix from Microsoft—when that happens, re-evaluate staged deployment plans and resume routine patching only after validation.
Source: Windows Report https://windowsreport.com/windows-1...ok-for-pop-accounts-microsoft-confirms-issue/
Microsoft shipped KB5074109 as the January 2026 security and quality rollup for Windows 11. The update was intended to address multiple issues—including a fix for devices with Neural Processing Units (NPUs) that were consuming power while idle and changes to Secure Boot certificate deployment—but it has also been linked to a set of regressions affecting several areas of Windows client functionality. Administrators and users reported problems ranging from Remote Desktop credential prompts to application hangs; within days Microsoft added a formal support notice for the Outlook POP issue and opened investigations. KB5074109 covers both Windows 11 version 24H2 and 25H2, and installs as OS builds 26100.7623 (24H2) and 26200.7623 (25H2). The Outlook-specific support advisory was posted and updated by Microsoft on January 15, 2026; their guidance identifies the problem as emerging and notes that Outlook and Windows teams are actively investigating. What went wrong: how KB5074109 affects Outlook POP profiles
Symptoms reported by users
Users have reported consistent symptoms after installing KB5074109:- Outlook does not exit correctly — closing the application leaves background processes running so Outlook cannot be restarted without a reboot or manual process termination.
- Hangs and freezes — Outlook becomes non-responsive during normal operations such as sending mail, opening folders, or accessing profile data.
- Sent items missing or not being recorded reliably — messages may be delivered but do not appear in Sent Items in affected profiles.
Technical surface area likely involved
At present Microsoft has not published a definitive root-cause analysis for the Outlook POP regression. Public discussion and telemetry indicate the problem is related to Outlook’s shutdown and profile handling logic under the updated Windows environment, but that explanation remains provisional until Microsoft publishes a technical update or hotfix. Until then, confirmable facts are limited to observed symptoms and Microsoft’s acknowledgment that the issue is under investigation. This distinction matters: there are credible user reports and a Microsoft notice, but the exact code path or conflicting component has not been disclosed.Who is affected
Consumer vs. enterprise
- Individual/Home users running Outlook with POP profiles can be impacted. Many consumer reports come from people with POP accounts for providers such as Yahoo or ISP-hosted mailboxes.
- Managed/Enterprise devices are also affected. In some cases enterprises deploying the January patch at scale saw widespread user impact and raised urgent support tickets. Microsoft’s support notices and forum activity demonstrate that the problem is not purely isolated to unmanaged PCs.
Platforms and builds
The problem has been observed on devices that received the January 13, 2026 KB5074109 update—Windows 11 builds 26100.7623 and 26200.7623. If a machine has not installed that specific cumulative update, it is unlikely to experience this regression. Confirm the installed build via Settings → System → About or by running winver.exe.Likely configurations at higher risk
Based on current reports (community and corporate), the most commonly affected setups are:- Desktop Outlook profiles using POP/SMTP (not modern Exchange or Microsoft 365 account configurations).
- Profiles with older PST/OST structures or large local data stores—though this is anecdotal and not yet validated as a causal factor. Treat such provider-specific observations as unverified until Microsoft releases formal details.
Why this matters: impact and risk assessment
Classic, desktop Outlook remains a dominant mail client in many enterprises and for many individuals who rely on POP-based mail delivery. A Windows update that causes Outlook to hang or fail to exit cleanly has real operational impacts:- Productivity loss: Users unable to restart Outlook lose access to new mail, sent-item tracking, and other essentials. This can be especially damaging for small businesses that still use POP mailboxes.
- Support overhead: IT help desks see a spike in tickets for “Outlook not responding” or “Outlook won’t restart,” which strains resources during a mass rollout of updates. Community threads show administrators spending hours rolling back updates or performing system restores.
- Operational continuity: In managed environments with automatic updates enabled, a problematic cumulative update can propagate quickly unless IT departments intervene with hold policies or targeted mitigations.
What Microsoft has said
Microsoft has published a support advisory acknowledging the Outlook POP regression and marking the issue as “Investigating.” The advisory confirms the problem appeared after installing the January 13, 2026 update (KB5074109) and that the Outlook and Windows teams are collaborating to diagnose the behavior. Microsoft’s page encourages affected users to follow the discussion in the Microsoft Learn forums and promises updates when more information is available. Separately, the KB5074109 release notes list several fixes and improvements—most notably the NPU power behavior fix and Secure Boot deployment enhancements—showing that the update itself contains legitimate platform-level improvements even as it introduced regressions in certain scenarios. Microsoft has used Known Issue Rollback (KIR) mechanisms and, where necessary, out-of-band updates to remediate other windows update regressions in recent months; an out-of-band or follow-up fix for this Outlook issue is the likely remediation path.Workarounds and mitigation strategies
Until Microsoft issues a formal fix, administrators and users have a few practical options to reduce impact or restore functionality. Each option carries trade-offs—particularly in managed environments—so weigh the business considerations before implementing.Short-term user/workstation steps
- Restart and terminate lingering Outlook processes: Open Task Manager, end any Outlook.exe and Office-related background processes, then reopen Outlook. This can be a temporary workaround but is not a scalable fix.
- Start Outlook in Safe Mode: Launch Outlook with safe mode (hold Ctrl while opening or run outlook.exe /safe) to determine whether add-ins exacerbate the issue. If safe mode avoids hangs, progressively disable add-ins and test.
- Use Outlook Web Access (OWA) or provider webmail: For immediate mail access, use webmail until a patch is available. Microsoft and community posts have recommended webmail as a stopgap.
- Repair Office installation: Run the Office online repair from Programs and Features—this resolves some post-update corruption scenarios but may not address the underlying compatibility fault introduced by the KB.
Uninstalling KB5074109
Some users report that uninstalling KB5074109 restores normal Outlook behavior. However, unlinking the update is not always straightforward:- Standard uninstall: Settings → Windows Update → Update history → Uninstall updates may show KB5074109 on some systems—but on others it may not be removable because the package includes a servicing stack update (SSU) or because it’s a combined rollup.
- DISM remove-package: Advanced users and administrators have used DISM to enumerate and remove the rollup package via command line. The Microsoft Q&A thread contains step-by-step community guidance for using dism.exe /online /get-packages followed by dism /online /remove-package /PackageName:<package> to remove the offending rollup. This method requires administrative privileges, careful package selection, and a system reboot. It may fail if other updates depend on the package or if the package is protected. Proceed only when you can accept the consequences of removing a cumulative security update.
- Removing a cumulative security update can reduce system security and may reintroduce vulnerabilities fixed by the patch.
- In managed environments, uninstalling an update may violate policy or complicate update compliance reporting. Coordinate with security teams before rollback.
Enterprise-level mitigations
- Hold deployment: For organizations still rolling out updates, apply a temporary block to KB5074109 and continue testing until a vendor fix is released. Staging updates in a ring-based model prevents widespread impact.
- Escalate through Microsoft support: Open a support ticket for production-impacting outages—Microsoft has dedicated channels for enterprise customers and may expedite a resolution.
- Work with Known Issue Rollback (KIR): Microsoft uses KIR to roll back problematic changes remotely for targeted device subsets in some scenarios. Monitor Microsoft’s enterprise communications for KIR guidance specific to this issue; at publication KIR was referenced for other KB5074109 regressions and may be part of the remediation toolkit.
Step-by-step: how to check whether you’re affected
- Verify the installed OS build: run winver.exe or check Settings → System → About to confirm you’re on 26100.7623 or 26200.7623.
- Observe Outlook behavior: confirm if Outlook remains running after you close it, or if Sent Items are missing despite successful sends.
- Check Event Viewer for Outlook crash or hang events: Windows Logs → Application may contain Event 1000 or related hang/error entries that help diagnose the type of fault. Microsoft community moderators have requested these logs to triage the issue.
- If confirmed and urgent: consider the mitigations above—webmail, safe mode, or controlled uninstall under IT guidance.
What to expect next: Microsoft’s likely remediation path
When Microsoft acknowledges a regression introduced by a security or cumulative update, the typical remediation sequence includes:- Investigation and telemetry analysis by the product teams (already in progress).
- Out-of-band (OOB) update or hotfix if the problem is severe and widespread; Microsoft has used OOB updates in the past for similar regressions. Several community threads and news outlets noted that Microsoft often releases a follow-up patch within days when fixes are required.
- Known Issue Rollback (KIR) for targeted, reversible changes when feasible. KIR is often used when a behavior change introduced by an update must be disabled for impacted devices.
Practical recommendations (concise checklist)
- For home users: If you rely on POP Outlook and see problems, temporarily use webmail or Outlook Web Access, try Outlook safe mode, and consider uninstalling the update only if you understand the security implications or with vendor guidance. Back up Outlook PST files before making major changes.
- For IT administrators: Pause or stage KB5074109 deployments, establish a communication channel to affected users, and consider blocking the update in your management tooling until Microsoft releases an official fix. Escalate to Microsoft support for production-impacting incidents.
- For security teams: Balance the operational risk of uninstalling a security update against the productivity loss. If rollback is required, document the change, monitor endpoints for re-exposures, and plan timely reinstallation when a patch is available.
Strengths and weaknesses of Microsoft’s response so far
Notable strengths
- Rapid acknowledgment: Microsoft posted an advisory recognizing the Outlook POP behavior and that the teams are investigating—this transparency is important for IT planning.
- Track record of remediation mechanisms: Microsoft has multiple tools—KIR, out-of-band updates, and staged deployments—to correct high-impact regressions, providing several avenues for a timely fix.
Risks and weaknesses
- Insufficient technical detail yet: The advisory confirms the symptom set but does not provide a root-cause analysis or a timeline for a patch, leaving administrators to weigh rollback risks without full information.
- Patch complexity: Cumulative updates that include SSUs or combined packages complicate uninstall procedures, creating potential friction for users and support teams trying to recover. Community threads show that some users cannot uninstall via standard GUI paths and must use advanced DISM commands. This raises the bar for recovery.
Final analysis and guidance
The KB5074109 incident is a timely reminder of the trade-offs inherent in modern cumulative update models: bundling fixes improves security and simplifies patching, but when a regression slips through, the combined nature of updates can complicate quick rollback paths. Microsoft’s public acknowledgment and the existing toolset for mitigation (KIR, OOB updates, support escalation) are positive signs. At the same time, the lack of a published root cause and the complexity of uninstalling the package create a practical gap for organizations needing immediate remediation.Actionable takeaways:
- Treat KB5074109 as blocked in production rings until Microsoft confirms a fix, and prioritize systems that run legacy POP-based Outlook profiles for testing.
- For affected end users, use webmail or OWA and run Outlook in safe mode as temporary measures; involve your help desk for any rollback steps that require elevated privileges.
- Document any rollback and security trade-offs, and plan to reapply security updates when Microsoft issues a corrected package or an OOB fix.
Outlook users and administrators should monitor Microsoft’s support pages and the Microsoft Learn forums for updates; prepare rollback procedures for critical workstations; and test any remedial steps in a controlled environment before applying them broadly. The coming days are likely to reveal either a KIR deployment or an OOB hotfix from Microsoft—when that happens, re-evaluate staged deployment plans and resume routine patching only after validation.
Source: Windows Report https://windowsreport.com/windows-1...ok-for-pop-accounts-microsoft-confirms-issue/
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