Higher-Ed is all over getting sensitive data off of user's workstations and email accounts and it would be handy to have Zimbra identify for us which messages contain sensitive information.

Zimbra Search help Zimbra Web Client Search Tips - Zimbra :: Wiki shows
that you can search for sensitive data in your mailbox by using the search
terms "has:ssn" and "has:credit-card", but on our server those searches don't
produce any results.

Does anyone know how to enable those object types on our server?

I entered this in bugzilla, too:
Bug 44016 – How do you search for sensitive data in web client (i.e., ssn and/or credit-card numbers)