Microsoft has officially announced the retirement of Exchange Web Services (EWS) for Exchange Online, beginning in October of 2026 and ending April 1, 2027. This change has important implications for organizations that rely on third-party applications accessing Public Folder data, especially contacts and calendars.
TL;DR – EWS Retirement & Public Folders
What’s happening: Microsoft is retiring Exchange Web Services (EWS) in Exchange Online.
Key dates:
| Date | What happens |
| March 1, 2026 | F1, F3, and Kiosk licenses already blocked from EWS |
| End of August 2026 | Deadline to set EWSEnabled=True + AppID AllowList if you need EWS past October |
| September 2026 | Microsoft pre-populates allow lists based on tenant usage |
| October 1, 2026 | EWS starts being disabled tenant-by-tenant |
| April 1, 2027 | EWS fully disabled – no exceptions |
Scope: Exchange Online only. On-premises Exchange Server is not affected.
Public Folder impact: Graph will not offer programmatic Public Folder CRUD. EWS-based Public Folder syncs will stop working and cannot simply be re-pointed at Graph.
Recommended replacement: Shared mailboxes (Graph-supported, modern auth), or a CRM for customer-facing contacts.
What to do now: Run EWS Usage Reports → identify Public Folder dependencies → get vendor Graph plans → migrate to shared mailboxes with CiraHub keeping data in sync during the move.
What is Changing?
EWS has long been used by third-party applications and custom integrations to access Exchange Online data such as contacts, calendars, mailboxes, and Public Folders. As part of Microsoft’s broader security and modernization initiative, Microsoft begins disabling EWS across Exchange Online tenants on October 1, 2026, with EWS fully disabled on April 1, 2027. The rollout is tenant-by-tenant, controlled by the EWSEnabled property: any tenant still set to Null on October 1, 2026 is switched to False, which blocks EWS for every application.
Important: This change applies only to Exchange Online. Exchange Server on-premises is not affected.
Impact on Public Folders
One of the most significant consequences of the EWS retirement is its effect on Public Folders. Many third-party tools rely on EWS to read or synchronize Public Folder contacts and calendars. When EWS is disabled:
- Third-party applications will lose all EWS-based access to Public Folders
- Public Folder data will no longer be accessible for syncing or integration
- Existing workflows built around Public Folder contacts and calendars may break
This isn’t a temporary gap. Microsoft has decided to restrict programmatic Public Folder access to supported Outlook clients and bulk import/export only, and has confirmed it will not provide APIs for programmatically creating, reading, updating, or deleting Public Folders after October 2026. There is no Graph equivalent coming for these integrations.
Who Should Be Planning Now?
You should start planning immediately if:
- Your organization uses third-party apps that read from or write to Public Folder contacts or calendars
- Public Folders are part of your CRM, address book, or scheduling workflows
- You depend on bi-directional sync between Public Folders and other systems
Although October 2026 may seem far away, migrating shared data structures—especially those tied to business processes—takes time, testing, and coordination.
The August 2026 Deadline Most Teams Are Missing
Microsoft’s rollout is controlled per tenant by the EWSEnabled setting. If you need any EWS-based app to keep working past October 1, 2026, you must set EWSEnabled=True and configure an AppID AllowList before the end of August 2026. If you don’t, Microsoft pre-populates an allow list for your tenant in September 2026 based on observed usage – which may not match the apps you actually depend on. Note that F1, F3, and Kiosk licenses already lost EWS access on March 1, 2026. Even with an allow list, this only buys time: EWS is fully disabled on April 1, 2027.
How to Audit Your EWS Exposure (Before You Migrate)
- Open the EWS Usage Reports in the Microsoft 365 admin center to see which apps in your tenant are calling EWS.
- Run the EWS Analyzer tool against internal scripts and custom integrations.
- Ask each third-party vendor for their Graph migration plan and timeline in writing.
- Flag every workflow that touches Public Folder contacts or calendars – those have no Graph replacement and need a new data source, not a code update.
- Set an internal target to have migrations underway, not merely planned, well before the October window.
Recommended Migration Options
Shared Mailboxes (Recommended)
A shared mailbox is often the best replacement for Public Folders when working with contacts and calendars. Shared mailboxes are fully supported by Microsoft Graph, ideal for shared contact lists and calendars, compatible with modern authentication, and supported by most third-party tools.
CRM or Centralized Contact Repositories
In some cases, organizations may choose to migrate Public Folder data into a CRM system, or another centralized contact repository, especially when Public Folder contacts are customer- or partner-facing.
How CiraHub Can Help
CiraHub is designed to help organizations adapt to the EWS retirement by providing flexible, multi-way contact and calendar synchronization.
With CiraHub, you can:
- Migrate Public Folder contacts and calendars to a shared mailbox
- Keep data synchronized during and after migration
- Replace Public Folder dependencies with modern, supported data sources
- Integrate shared contacts and calendars with popular CRM platforms
Supported CRM Connectors
CiraHub supports synchronization with the following CRMs:
- Salesforce
- HubSpot
- ActiveCampaign
- Pipedrive
- Zoho CRM
- Procore
- DealCloud
- QuickBooks
- Clio
- Workday
- Everbridge
- Copper
Find the Right Solution Before EWS Is Turned Off
Public Folder dependencies don’t have to become a disruption. Find a solution that helps you replace EWS‑based integrations, migrate to shared mailboxes or CRMs, and maintain reliable contact and calendar sync across devices – before October 2026.
Frequently Asked Questions
When exactly is EWS being turned off?
Microsoft begins disabling EWS in Exchange Online on October 1, 2026, and fully disables it on April 1, 2027.
Does EWS retirement affect on-premises Exchange Server?
No. It applies only to Exchange Online / Microsoft 365. Exchange Server on-premises is unaffected.
Can I keep EWS running after October 2026?
Only temporarily: set EWSEnabled=True and configure an AppID AllowList before the end of August 2026. EWS still ends April 1, 2027.
Will Microsoft Graph support Public Folders after EWS retires?
No. Microsoft has confirmed it won’t provide APIs for programmatic Public Folder create/read/update/delete after October 2026; access is limited to supported Outlook clients and bulk import/export.
What should replace Public Folders for shared contacts and calendars?
Shared mailboxes are the recommended replacement – fully supported by Graph, compatible with modern authentication, and supported by most third-party tools. CRMs work for customer-facing contact data.
Will my Public Folder sync break?
If your tool uses EWS, yes. Ask your vendor for their Graph plan, and migrate Public Folder contacts/calendars to a shared mailbox before the deadline.
