Moving Public Folder Contacts to a Shared Mailbox Before EWS Goes Away
If your team keeps a company contact list in an Exchange Online (Microsoft 365) public folder, the clock is running. Starting October 1st, 2026, Microsoft begins switching EWS off in Exchange Online, tenant by tenant, and on April 1st, 2027, it is fully and permanently disabled, with the tenant-level switch removed.
That matters for public folders specifically because Microsoft Graph, the API replacing EWS, has no public folder support. Any app, sync tool, or script that reads public folder contacts today will lose access, including SyncPenguin. The practical fix is to move those contacts into a contacts folder inside a shared mailbox, which MS Graph can fully support.
Below we present the steps required to make the switch. Note that no action needs to be taken in case of Exchange on-premises, as only Exchange Online is affected.
1. Export the public folder contacts
You’ll need classic Outlook for Windows, because it has the most complete public folder and import/export support.
- In classic Outlook, open the Folder pane, expand Public Folders → All Public Folders, and find your contacts folder.
- Go to File → Open & Export → Import/Export → Export to a file.
- Choose Outlook Data File (.pst), select the public folder contacts folder, and save the PST file to any location.
Use PST format rather than CSV, as CSV drops contact photos, contact groups, and some fields, and requires manual field mapping on import. PST exports as much information as possible.
2. Create the shared mailbox
In the Microsoft 365 admin center, go to Teams & groups → Shared mailboxes → Add a shared mailbox, give it a name (for example, “Our Shared Mailbox”), then add the members who need access.
Or, you can also do it with an Exchange Online PowerShell script:
Connect-ExchangeOnline
New-Mailbox -Shared -Name "Our Shared Mailbox" `
-DisplayName "Our Shared Mailbox" -Alias oursharedmailbox
Add-MailboxPermission -Identity oursharedmailbox`
-User [email protected] -AccessRights FullAccess -InheritanceType AllShared mailboxes under 50 GB don’t need a license to work without any issues.
Full Access permission automatically adds the mailbox to each member’s Outlook within an hour or so due to propagation delay.
3. Create the contacts folder
Once the shared mailbox shows up in Outlook, right-click it in the Folder pane, choose New Folder, name it (for example, “Company directory”), and set Folder contains to Contact Items. Alternatively, you can simply use the shared mailbox’s built-in Contacts folder.
4. Import the contacts
The most reliable way to import into a shared mailbox is to open the PST and copy the items across:
- In classic Outlook, go to File → Open & Export → Open Outlook Data File and open your exported PST.
- Switch to the People view, open the contacts folder in the PST, select all (Ctrl+A), and drag or copy the contacts into the new folder in the created shared mailbox.
- Check that the item count matches the original public folder, then close the PST.
Point your apps to the new folder
Update any integrations to read from the shared mailbox instead of the public folder. Finally, set the old public folder to read-only for a transition period so nobody keeps editing the stale copy, and remove it once everyone has switched over.
