We have a Exchange 2010 SP3 RU12 environment. When I try to add a delegate to one room mailbox on the "Resource Policy Tab" I get this error:
MapiExceptionNonCanonicalACL: Unable to modify table. (hr=0x80004005, ec=2409)
Via Powershell:
[PS] C:\Windows\system32>set-calendarprocessing -Identity RoomB -ResourceDelegates "user@domain.com"
Failed to save MapiAclTable table.
+ CategoryInfo : NotSpecified: (0:Int32) [Set-CalendarProcessing], StoragePermanentException
+ FullyQualifiedErrorId : 58CE12D9,Microsoft.Exchange.Management.StoreTasks.SetCalendarProcessing
I downloaded EXFolders per this thread and cleared the permissions, but I still get the error.
I also tried moving the mailbox to a different database and running a repair on it.