Cannot expand the folder. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed.
Cannot expand the folder. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed.
Hi @JustinMicheal-7973,
According to the documentation below, additional configuration might be required to use delegated mailbox permissions in a hybrid deployment with Exchange 2016:
Configure Exchange to support delegated mailbox permissions in a hybrid deployment
Please open the Exchange Management Shell on the Exchange 2016 server and then run the following command to check if ACLable object synchronization has been enabled in your environment:
Get-OrganizationConfig | fl ACLableSyncedObjectEnabled
If the result in the output is "False", which means ACLable object synchronization hasn't been enabled, you would need to:
Follow the guidance in the article above to enable ACLable object synchronization at the organization level.
Enable ACLs on mailboxes that have already been moved to Exchange Online before ACLable object synchronization was enabled at the organization level, see Enable ACLs on remote mailboxes.
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