Challenge
When backing up public folders using Veeam Backup for Microsoft 365 the following error occurs:
Processing mailbox PublicFolderMailbox@xxxxxxxx.onmicrosoft.com failed with error:
Failed to synchronize item changes in folder: FOLDERNAME..
Access is denied. Check credentials and try again., ICS synchronization failed.
Cause
Either of the following conditions may cause the error:
Public folders are not located under the IPM_SUBTREE folder.
The Veeam service account lacks permission to access public folders.
Solution
Confirm Public Folder is Located Under IPM_SUBTREE
Veeam Backup for Microsoft 365 only supports backing up public folders located under the IPM_SUBTREE folder. Other locations are not supported (e.g., NON_IPM_SUBTREE).
To check if the public folder is located under the IPM_SUBTREE folder, run the following cmdlet and specify credentials used in Veeam Backup for Microsoft 365.
More Information
PowerShell Scripts
All PowerShell scripts provided above are intended to automatically retrieve and assign necessary permissions to ensure that no public folders are missed.
Please be aware that the commands and parameters may be altered by Microsoft in the future, which may break these scripts.
No support is provided by Veeam for these scripts. Should they fail, we ask that you please get in touch with Microsoft support.
These scripts may be updated periodically to reflect future changes in the Microsoft 365 PowerShell Environment.
