If you are migrating your users mailboxes from Exchange 2010 to Exchange 2013 then you may come across the following problem. When you migrate your mailboxes, one or a number of mailboxes may generate the following error. Where X is the mailbox it has failed on and X2 is the total number of mailboxes.
Transient error StorageTransientException has occurred. The system will retry (x/x2)
Additional error information may contain.
Error: MigrationPermanentException: Error: Cannot open mailbox /o=First Exchange Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=S116/cn=Microsoft System Attendant. --> MapiExceptionMailboxQuarantined: Unable to open message store. (hr=0x80004005, ec=2611) Diagnostic context: Lid: 55847 EMSMDBPOOL.EcPoolSessionDoRpc called [length=132] Lid: 43559 EMSMDBPOOL.EcPoolSessionDoRpc returned [ec=0x0][length=232][latency=0] Lid: 52176 ClientVersion: 15.0.620.20 Lid: 50032 ServerVersion: 15.0.620.6020 Lid: 23226 --- ROP Parse Start --- Lid: 27962 ROP: ropLogon [254] Lid: 17082 ROP Error: 0xA33 Lid: 26937 Lid: 21921 StoreEc: 0xA33 Lid: 27962 ROP: ropExtendedError [250] Lid: 1494 ---- Remote Context Beg ---- Lid: 50608 Lid: 32848 dwParam: 0x14 Lid: 61416 StoreEc: 0xA33 Lid: 56872 dwParam: 0xFE Lid: 42712 StoreEc: 0xA33 Lid: 10786 dwParam: 0x0 Msg: 15.00.0620.016:s116 Lid: 1750 ---- Remote Context End ---- Lid: 26849 Lid: 21817 ROP Failure: 0xA33 Lid: 26297 Lid: 16585 StoreEc: 0xA33 Lid: 32441 Lid: 1706 StoreEc: 0xA33 Lid: 24761 Lid: 20665 StoreEc: 0xA33 Lid: 25785 Lid: 29881 StoreEc: 0xA33
Exchange Mailbox Poisoned
You are seeing this error because the mailbox that has failed to migrate is in a poisoned state and has been quarantined. A mailbox may be tagged as poisoned for numerous reasons such as corrupt attachments and emails or a virus or malware has been found in the mailbox. You have two options, you can either delete the mailbox or remove the poisoned state of the mailbox.
Removing a Mailbox From Quarantine
To remove a mailbox from quarantine in Exchange 2010 and Exchange 2013 we first need to get its GUID. To do so run the following command. Replacing username with the username of the mailbox that has been quarantined. Then make a note of the GUID of the mailbox.
get-mailbox statistics -identity | fl
Now that you have the GUID of the mailbox we need to browse to the following key in the registry and remove the key that mentiones the GUID.
HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeIS\\Private-{db guid}\QuarantinedMailboxes\{the mailbox guid}
One you have removed the offending GUID then you need to restart IIS with the following comand.
iisreset
Once done you will be able to migrate the mailbox as it is no longer quarantined.