Last updated: October 1, 2026
The quick answer
October 2026 brings four Microsoft changes that reach ordinary users: Exchange Web Services is being switched off in stages from October 1, which can break Microsoft 365 work email in Apple Mail on the Mac; Publisher is no longer available to Microsoft 365 subscribers; and on October 13, Office 2021 and Windows 11 version 24H2 (Home and Pro) stop getting security updates. Most people only need to update Windows, move any Publisher files and, if Mac Mail stops syncing, switch to Outlook for now.
What happened
Several long-announced Microsoft retirement dates land within the same two weeks. None of them is a surprise to IT departments, but together they can catch home users and small businesses off guard.
| Date | What changes | Who notices |
|---|---|---|
| From October 1 | Exchange Web Services (EWS) starts being disabled in Exchange Online, in phases | Mac users reading Microsoft 365 work email in Apple Mail or Calendar |
| October 1 | Publisher can no longer be used by Microsoft 365 subscribers | Anyone with flyers, newsletters or cards in .pub files |
| October 13 | Office 2021 reaches end of support | People who bought Office 2021 as a one-time purchase |
| October 13 | Windows 11 version 24H2 Home and Pro stop receiving updates | PCs that have not moved to a newer Windows 11 version |
What changes for you
Apple Mail and Microsoft 365 work accounts
EWS is an old connection method that some apps use to sync Microsoft 365 email, calendars and contacts. Microsoft stopped developing it years ago and is moving everyone to its newer Microsoft Graph interface. MacRumors reports that Apple Mail and Calendar on the Mac still rely on EWS for these accounts, so they may stop syncing once your organization’s turn comes. Microsoft is rolling the change out gradually, with a final shutdown on April 1, 2027.
The iPhone and iPad Mail apps are not affected because they use a different protocol, and on-premises Exchange servers are not part of this change. MacRumors also reports that Apple says it is working with Microsoft to move its Mac apps to Graph in a future macOS 27 update, without a date. Current versions of Outlook for Windows, Mac, mobile and the web are expected to keep working, according to university IT guidance such as Cornell’s.
Publisher
Microsoft’s support page says Microsoft 365 subscribers can no longer access Publisher after October 1, 2026, which means you cannot open .pub files with it through your subscription. People who own Office 2021 or 2024 as a one-time purchase can keep using Publisher, but it will not receive support. Microsoft suggests Word and PowerPoint as replacements.
Office 2021 and Windows 11 24H2
After October 13, Microsoft will no longer provide bug fixes, security fixes or technical support for Office 2021. The apps keep working, but new vulnerabilities will not be patched. On the same day, Windows 11 version 24H2 Home and Pro stop receiving monthly updates. TechRepublic notes that Enterprise and Education editions of 24H2 are supported until October 12, 2027, and that Home and Pro users cannot buy extended updates for this version.
What to do now
- Check your Windows version. Open Settings > System > About. If it says 24H2, go to Settings > Windows Update and select Check for updates. Microsoft moves consumer PCs to a newer version automatically, but you can start it yourself. Our guide to the Windows 11 2026 Update explains what the newest release adds.
- Rescue your Publisher files. If you still have Publisher installed through another license, open each file and use File > Save As to save a PDF copy. Then rebuild anything you still edit in Word or PowerPoint.
- If Mac Mail stops syncing work email, install Outlook for Mac or use Outlook on the web for that account. Ask your IT team whether they have temporarily kept EWS enabled, which administrators can do until the final cutoff.
- Plan your Office 2021 replacement. Options include a newer one-time Office purchase or a Microsoft 365 subscription. Free alternatives exist too, but test them with your documents first.
While you are updating devices, also make sure your iPhone or Mac has Apple’s latest security fix. See our guide to iOS 26.7.1.
Who it affects and who it doesn’t
- Affects: Mac users with Microsoft 365 work or school email in Apple Mail, Publisher users on Microsoft 365, Office 2021 owners and Windows 11 24H2 Home or Pro PCs.
- Affects later: organizations that temporarily re-enabled EWS, which still face the April 1, 2027 shutdown.
- Doesn’t affect: personal Outlook.com accounts on iPhone or iPad, people using current Outlook apps, PCs already on a newer Windows 11 version and Microsoft 365 users who never used Publisher.
FAQ
Will Office 2021 stop working on October 13?
No. Microsoft says the apps may continue to function, but they will no longer get security fixes, so the risk of using them grows over time.
Will my iPhone Mail app lose my work email?
Not because of this change. According to MacRumors, iPhone and iPad Mail use Exchange ActiveSync rather than EWS. The disruption is limited to the Mac apps.
Can I still open old .pub files?
Only with a one-time-purchase version of Publisher, such as from Office 2021 or 2024. Microsoft 365 subscribers lose access, so convert files to PDF while you still can.
Sources
- MacRumors: Apple Mail on Mac may stop syncing Microsoft 365 accounts
- Cornell IT: Prepare for EWS retirement
- Microsoft Support: Publisher will no longer be supported after October 2026
- Microsoft Support: End of support for Office 2021
- TechRepublic: Windows 11 24H2 Home and Pro support ends October 13
- Office Watch: October 2026 Microsoft 365 Office changes
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