Overview
There are several commands which affect the Enterprise Vault end-user experience which can be used in a migration with Archive Shuttle. This article explains those commands, and how they can be combined.
Details
The following commands affect the end-user experience of Enterprise Vault:
DisableMailbox – This command builds and executes an EVPM script to disable a mailbox from archiving. It will not work with a mailbox which is in Office 365. After a subsequent Enterprise Vault mailbox sync, the Outlook client will show Search and Help buttons on the Enterprise Vault toolbar.
ZapMailbox – This command builds and executes an EVPM script to perform a ‘Zap’ on a mailbox. It will not work with a mailbox which is in Office 365
DisableOrphanedArchive – This command executes SQL commands to set an Enterprise Vault archive to closed and the archiving state (MbxArchivingState) to disabled.
DeleteEVConfiguration – This command removes the Enterprise Vault hidden messages from a mailbox. It will not work with a mailbox which is in Office 365
RemoveVirtualVault – This command connects to a mailbox and modifies the Enterprise Vault hidden message so that at the next restart of Outlook the Enterprise Vault Outlook Addin will remove Virtual Vault from the Outlook profile.
RemoveEVButtons – This command connects to a mailbox and modifies the Enterprise Vault hidden message so that the Enterprise Vault buttons on the Outlook toolbar are removed
Office365DeleteEVConfiguration – This command removes the Enterprise Vault hidden message from a mailbox. It is specifically for Office 365 based mailboxes

Rickyoh wrote: Thanks BSOD'D. Ok it turns out that the last action which I did, which was to reinstall the Enterprise Vault Add In for Outlook, did the trick. When using Outlook 2010 or earlier and having Enterprise Vault 9.x and Symantec Encryption Desktop installed, additional IMAP accounts in Outlook will not work correctly. The account storage.pst for the IMAP account is created multiple times, mail can not be accesses in the IMAP account. This workaround is now working. It's probably available from Symantec if anyone else is looking for it. I haven't received confirmation, however from observation and minor feedback, it seems that the Enterprise Vault server may have been in maintenance mode while this wasn't working. If the outlook intermittently disconnect, it maybe caused by the mapi limits create a Maximum Allowed Sessions Per User in the below HKEYLOCALMACHINE SYSTEM CurrentControlSet Services MSExchangeIS ParametersSystem set the value 64. Check what is throttling policy for EV in exchange.

Enterprise Vault Outlook 2016 Not Showing Up

Enterprise Vault Outlook Not Working

Notes:
– DeleteEVConfiguration (and Office365DeleteEVConfiguration) should not be used in the same workflow as RemoveVirtualVault. They are mutually exclusive.
– DeleteEVConfiguration (and Office365DeleteEVConfiguration) should not be used in the same workflow as RemoveEVButtons. They are mutually exclusive.
– To disable the Enterprise Vault Outlook experience, it is recommended to perform: DisableOrphanedArchive, RemoveVirtualVault and RemoveEVButtons as part of the stage 2 workflow (along with other appropriate commands)