Deleted Vault emails are gone permanently?

If you accidentally delete an email or a bunch of email from a vault archive, those emails are gone permanently correct? there any ways to restore them? There anyways to find out if those emails were infact deleted?

I have an archive that appears that the last 3 years worth of email is gone. Their inbox shows the latest email is late 2012. However their Deleted Items folder shows current archived stuff..

They are on the same Vault policy as 1,000+ other people so the only thing I can think of is they accidentally deleted a bunch of email.