--query to find mailboxes using a storage service on a different computer.
select A.ArchiveName, CE.ComputerName as 'Comp entry for task', CE2.ComputerName as 'Comp entry for storage' 
from ExchangeMailboxEntry EME
inner join exchangemailboxstore EMS on EME.mbxstoreidentity  = EMS.mbxstoreidentity
inner join exchangeserverentry ESE on ESE.ExchangeServerIdentity = EMS.ExchangeServerIdentity
inner join archivingretrievaltask ART on ART.ExchangeServerEntryid = ESE.ExchangeServerEntryid
inner join task T on T.TaskEntryID = ART.TaskEntryID
inner join computerentry CE on CE.ComputerEntryID = T.ComputerEntryID
inner join root R on R.VaultEntryID = EME.DefaultVaultID
inner join archive A on A.rootidentity = R.RootIdentity
inner join vaultstoreentry VSE on VSE.VaultStoreEntryID = A.VaultStoreEntryID
inner join storageserviceentry SSE on SSE.ServiceEntryID = VSE.StorageServiceEntryID
inner join computerentry CE2 on CE2.ComputerEntryID = SSE.ComputerEntryID
where CE.ComputerEntryID != CE2.ComputerEntryID