You have a hybrid deployment of on-premises Microsoft Exchange Server and Microsoft Exchange Online in Office 365.
You configured legacy on-premises public folders for a hybrid deployment.
You create a shared mailbox that's located in Exchange Online.
You assign Full Access permissions to one or more users.
The user adds the shared mailbox as a second Exchange account in their existing Outlook profile.
In this scenario, the user is repeatedly prompted for credentials when they open Outlook.
Move the shared mailbox to the on-premises environment.
Outlook tries to connect to the legacy public folders for the shared mailbox account. An error message that resembles the following is found in the RPC Client Access service log for this connection attempt:
[LoginPermException] 'User SID: S-1-5-21-1458817636-171340609-1824194506-1199' can't act as owner of a MailUser object '/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=189bd14f1ede49d797785e8f20d55edf-Shared Mail' with SID S-1-5-21-1458817636-171340609-1824194506-1207 and MasterAccountSid S-1-5-10 (StoreError=LoginPerm)
Microsoft Exchange Online, Exchange Server 2016 Enterprise Edition, Exchange Server 2016 Standard Edition, Microsoft Exchange Server 2013 Enterprise, Microsoft Exchange Server 2013 Standard, Microsoft Exchange Server 2010 Enterprise, Microsoft Exchange Server 2010 Standard