Public Folders Not Syncing After EWS Retirement? Fix It Now

Written By Khushboo Maurya
Updated on October 28th, 2026

ⓘ Fact-checked and reviewed in accordance with our Editorial Policy

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As per the Microsoft article, EWS will be permanently shut down on April 1, 2027. This is the retirement of Exchange Web Services (EWS) in Exchange Online. This deprecation may affect the third-party applications that rely on EWS to access Exchange Online data, which include public folder contacts & calendars. If your CRM, phone system, or calendar sync app has stopped syncing the public folder data. Check its EWS dependency and plan an alternative before the retirement deadline. Therefore, this guide helps you resolve Exchange Online public folder sync issues with ease.

Table of Contents

Symptoms: Exchange Online Public Folders Not Syncing

Look at the symptoms that you may face, which indicate that your public folder is not syncing:

To begin with, your CRM contacts appear blank.
Phone system directories show Exchange Online public folder contacts not syncing.
Along with that, your shared calendar events are not syncing.
Pubic folder data remains available in Outlook but is missing in connected apps.
Apps show an Exchange Online public folder access denied error when they try to open contacts or calendars.

Why Public Folder Syncing Stops After EWS Cutoff

Microsoft is retiring Exchange Web Services in Exchange Online. Blocking of non-Microsoft app requests began October 1, 2026, tenant by tenant. Many third-party tools used EWS to read & write public folder contacts and calendars. Microsoft Graph has no general public folder create, read, update, delete support. So these syncs cannot simply be repointed. Impact depends on your app’s API and your tenant’s disablement date. Apps that use Graph alone are unaffected. [Microsoft Learn]

Can You Re-Enable EWS in Exchange Online?

Yes. Admins can check EWS status in Exchange Online PowerShell. Run Get-OrganizationConfig & review the EWSEnabled value. False means EWS is blocked. Setting it to true usually restores access within four hours. Microsoft says this works only at the time of the first disablement stage. Check the Exchange team blog and Message Center for current eligibility and deadlines. Re-enablement ends in April 2027. It is a temporary fix, not a permanent solution.

Identify Which Applications Depend on Public Folders

Make a list of every app connected to your Exchange Online setup. Don’t forget CRM tools, VoIP phone systems, and calendar sync apps.
Then go through your public folders one by one and note which ones hold contacts, calendars, or other shared data.
Then check each app’s sign-in method and API. Look for EWS use.
Finally, contact every vendor. Ask if their product is ready for the EWS retirement.
Request their Graph migration plan in writing.

Best Software to Backup Exchange Online Public Folder Data

Public folders often store shared contacts and calendars. Backing them up before EWS ends is wise. Cigati Exchange Server to PST Backup Tool can help to resolve the Exchange Online public folder sync issues. It exports Exchange Online, on-premises, & hybrid mailbox data into PST files. It covers primary, shared, archive, and public folder mailboxes. Admins get a local copy that is easy to open and store. Setup is simple. To move Public folder data to PST, look at the detailed guide on How to Export Public Folder to PST.

Exclusive Features of this software:

Back up primary, shared, archive, & public folder mailboxes together, without separate cycles.
Works with Exchange Online, on-premises servers, and hybrid setups in a single session.
Works with Exchange Server 2019, 2016, 2013, 2010, and even older versions, so you don’t need a separate tool for legacy servers.
The folder structure in the PST file is the same as in the original mailbox, so you can find and check any item quickly.
Preview your emails, attachments, and folders in the tool’s own window before the backup starts.
Don’t want the whole mailbox? Choose a date range, or pick only the item types you need, like emails, contacts, or calendars.
It remembers what was already saved in earlier runs and skips those items, which makes repeat backups much faster.
Duplicate emails are detected by comparing the sender, recipient, subject, and body, so your PST file doesn’t fill up with repeats.
Large PST files can be split into smaller parts, which makes them easier to store, move, and open.
You can add multiple mailboxes to one job and back them up together, saving a lot of time for admins.
Individuals use interactive sign-in. Admins use a Client ID and secret.
Rename destination folders and save to local disks, external drives, SAN, or NAS storage.
Get a log report after each job, plus 24/7 technical support.

To move your Exchange Online Public Folder data to PST. Look at how the step-by-step guide works to migrate data via Cigati Exchange Server to PST Backup Tool.

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Move Public Folder Data to an Application-Supported Source

Public folders may not stay a viable source for your apps. Ask each vendor which source it supports. Options include a shared mailbox, a user mailbox, or the CRM itself. Shared mailboxes work well for contacts & calendars. Map every field before you move data. Then migrate a small test group first. Check that sync works both ways. Validate the contacts, the events, the permissions and the folder contents. After the test should we roll out to everyone.

What Happens When EWS Is Fully Retired on April 1, 2027?

On April 1, 2027, EWS stops working in Exchange Online. Apps that still depend on it will fail. Syncs, calls, and calendar updates may break. Temporary re-enablement will not help after this date. Do not count on any extension. A PST file is only a backup. It is a static copy, not a live sync source. Finish app fixes early. Test every integration well before the deadline.

How to Prevent Future Exchange public folder synchronization issues

You must maintain an inventory of EWS-dependent applications.
Keep a verified backup of your critical public folder data, and open a few restored items to confirm the backup actually works.
Run a test of the new workflow first, and switch off the old integration only after the test passes.
Ask each software vendor in writing whether their product supports the API you plan to use.
Users regularly monitor Microsoft’s official announcements for changes.

Conclusion

Exchange Online public folder sync issues after the EWS retirement usually trace back to one cause: apps that read public folder contacts and calendars through EWS, which Microsoft is shutting down for good on April 1, 2027. Graph has no general public folder support, so these integrations can’t simply be repointed. Start by checking EWSEnabled with Get-OrganizationConfig. If the setting is still available to your tenant, re-enabling EWS buys a little time, but it ends in April 2027. Use that window to list every dependent app, get written Graph migration plans from each vendor, and move shared contacts and calendars to a source your apps support, such as a shared mailbox. Test with a small group before rolling out to everyone. Take a verified backup of your public folder data before you change anything. A PST copy, for example from the Cigati Exchange Server to PST Backup Tool, protects your contacts and calendars if a migration goes wrong, but it is a static copy and won’t keep any app in sync. Fix the integrations early and test them well before the deadline.

Frequently Asked Questions

Q1. Why did my public folder contacts stop syncing to my CRM or phone system?

Ans. Most third-party tools read public folder data through Exchange Web Services. Microsoft began blocking non-Microsoft EWS requests on October 1, 2026, tenant by tenant. If your tenant has reached its disablement date, those tools lose access even though the data is still intact in Outlook.

Q2. How do I check whether EWS is disabled in my tenant?

Ans. Connect to Exchange Online PowerShell and run Get-OrganizationConfig | Select EWSEnabled. A value of False means EWS is blocked for your organization.

Q3. Can I re-enable EWS, and how long does it take to work?

Ans. Yes, if your tenant is still eligible. Set EWSEnabled to $true with Set-OrganizationConfig. Access usually returns within about four hours. This is only a temporary fix, and re-enablement ends in April 2027. Check the Exchange team blog and Message Center for your eligibility and deadlines.

Q4. Can I switch the sync to Microsoft Graph instead?

Ans. Not for public folders. Graph has no general create, read, update, and delete support for them. Apps that use Graph alone are unaffected, but EWS-based public folder syncs need a different data source.

Q5. How do I find which apps depend on EWS?

Ans. For this, make a list of every connected app, that includes CRM tools, VoIP systems, & calendar sync utilities. Check each one’s sign-in method and API. Then ask the vendor in writing whether it uses EWS and when its Graph-based version will be ready.

Q6. Which source works best as a replacement for public folders?

Ans. Shared mailboxes work well for contacts & calendars. A user mailbox or the CRM itself can also work, depending on what the vendor supports. Map every field first, then pilot with a small group and confirm that sync works both ways.

About The Author:

Khushboo Maurya

Khushboo Maurya is a digital content and SEO professional focused on creating useful, search-friendly content that connects with the right audience. She specializes in content optimization, website growth, and practical SEO strategies that improve visibility, engagement, and organic reach.