Litigation Hold Procedure

Hi Everyone,

I'm looking for some kind of procedure to set up a Litigation Hold on mailboxes and archives.

I have a standard setup of 2 Exchange servers, a Enterprise Vault (first archive policy is "older than a year") and Discovery Accelerator set up on my infrastructure

i must put some mailboxes in legal hold in order to protect everything on it.

But i don't know how to achieve and be sure is "Legal compliant" (I know how to do it in Exchange, but not with Enterprise Vault).

I searched for a procedure or something like that, but didn't find anything.

Can someone help me ? 

Thanks