Symptoms:
1. Outlook Web Access shows: A problem occurred while you were trying to use your mailbox.
2. Outlook won’t connect to exchange.
Mailbox may be quarantined.
Removing mailbox from quarantine
1. Delete REG KEY on server:
HKLM\SYSTEM\CCS\Services\MSexchangeIS\Servername\Private-dbguid\Quarantined Mailboxes\ {Mailbox guid}.
2. Restart Microsoft Exchange Information Store Service