EWS, Publisher and Office LTSC 2021: three Microsoft retirements landing in the same month

Some months happen to bring three clean-up moments at once. This October is one of those for anyone running Microsoft 365. Exchange Web Services has been switched off tenant by tenant since 1 October, Publisher left the Microsoft 365 subscriptions that same day, and Office LTSC 2021 lost its final security updates on 13 October. Three products with little in common, yet the same advice applies to all of them: check what in your environment still leans on these components, before someone finds out the hard way.

None of the three is big news by itself. Microsoft always announces retirements like these well in advance through the Message Center. The risk is not the announcement, it is the old integration, the forgotten template, or the device nobody actively manages anymore that turns out to depend on one of them.

EWS: the API you probably do not know you are using

Exchange Web Services is the older programming interface that let applications reach an Exchange mailbox: syncing calendars, archiving email, a scan-to-email function on a multifunction printer, or a link between a CRM system and Outlook. Microsoft Graph has been the recommended replacement for years, with more modern authentication and finer-grained permissions, but many of those older integrations were built once and never touched again.

Since 1 October, Microsoft disables EWS in Exchange Online by default, tenant by tenant, unless an administrator had already set up an allow list of app IDs and explicitly enabled EWS before the end of August. If that did not happen in your tenant, access may already be gone or about to disappear. Re-enabling is still possible, but only temporarily: on 1 April 2027 EWS closes for good, with no exceptions. The change only applies to Exchange Online, an on-premises Exchange server keeps working with EWS as before.

Check the usage reports in the Exchange admin center or Graph to see which applications are still making EWS calls. Often these turn out to be older migration tools, a backup solution still leaning on the old protocol, or an internal script written by someone who has since left and has quietly kept running in the background. Start that migration to Graph now, not in March 2027, since vendors on the other end usually need their own time to rebuild the connection too.

Publisher: no new installs, and old files become inaccessible

Publisher was never the flagship of the Office suite, but plenty of organisations still have a flyer, a newsletter template, or an old business card design sitting in a .pub file somewhere. Since 1 October, Microsoft 365 subscribers can no longer open or edit those files through their subscription. Anyone still on the perpetual Office 2021 licence kept Publisher functional until 13 October, the day the rest of that suite also lost its final support.

The files themselves are not deleted, but without a working Publisher installation there is nothing you can do with them. Microsoft points to Word, PowerPoint, and Designer as replacements for new design work. The practical advice is simple: go through your archive of .pub files before you need one and cannot open it, and convert what you still need to Word, or to PDF if only the layout matters.

Office LTSC 2021: no ESU, no extension

On 13 October, support ended for Office LTSC 2021, including Project LTSC 2021 and Visio LTSC 2021, and for the standalone Office 2021 licence. Unlike Windows 10, Microsoft offers no Extended Security Updates programme for this one. The applications keep working after that date, but there will be no more security patches, bug fixes, or technical support.

That matters most for devices that run deliberately outside Microsoft 365, for example on an isolated network or on a machine that was never converted to a subscription for licensing reasons. For most organisations, Microsoft 365 Apps is the obvious replacement, with ongoing updates included in the subscription. For environments that intentionally run without a cloud subscription, say for compliance or network reasons, Office LTSC 2024 is the successor, supported until October 2029 under the same fixed lifecycle model.

One check instead of three separate notices

The coincidence of these three deadlines landing in the same month is not meaningful by itself, but it is a useful trigger. A quick inventory answers three questions at once. Which integrations, scripts, or multifunction printers still talk to Exchange through EWS instead of Graph? Are there .pub files sitting in shared folders or SharePoint sites that someone still intends to edit? And is there a machine somewhere running Office LTSC 2021 or older that nobody has on their list anymore, such as a point-of-sale terminal, a reception PC, or a laptop handed down from a former employee?

None of these three questions needs a large project. It takes about half an hour searching the right admin centres and a short list of what still needs converting. Not sure where to start, or would you rather have someone else run this inventory for you? Zarioh helps organisations manage their Microsoft 365 environment, from retirements like these to the broader security settings around them. Feel free to get in touch for a no-obligation conversation.