EV with Hitachi HCP retention problem

Hi @all,

we have now a brand new Hitachi HCP.
We want to migrate from our old centera to the new HCP.

We have a problem with the HCP.
One of our use cases in EV:
We use Enterprise Vault to archive our user mailboxes. The users have always the possibility to delete their archived mails / shortcuts. On Centera we configured the retention period to "forever" and at the vault store partion we set retentionmode to "never".

Now in the HCP the retention period "forever" set the mail objects to "deletion prohibited". So the user cannot delete these objects.
How can I configure ev, that users can delete their archived objects at HCP?

Update:
I´ve tried one solution from another thread:
Setting retention period to 0 days. And set "prevent automatic deletion of expired items".
This works but than we have an another problem. The user delete the item in his mailbox and in EV but the item remain in the HCP. This item will never be deleted in the HCP.