To start things off, I believe you are referring to spam quarantine and not PVO because there's no notification sent for emails going to PVO unless you have setup content filters or message filters with a notify action.
Second - Even if its PVO, end users will not have access to it directly, only administrators/operators or custom user roles can have access to it.
Considering it is spam quarantine, if an email with multiple recipients part of the same domain gets quarantined, it can always be released by specific recipient and they will receive them independently, while others wont.
Spam quarantine will still have a copy of the same message with other remaining recipients which can be released at a later stage
If the behaviour is different than explained above, I would recommend working with TAC