Zimbra integration feature

Anyone using this one?

Just curious, I tried in a lab test instance, and when I try to configure my creds I get:

Warning: Zimbra login error : Host violates local access rules

I already have LDAP authentication hitting the Zimbra ldap backend servers, as well as the nc mail client connects fine, all of that is working. Not sure we would need the integration feature, but thought it was worth a look. Curious if anyone is finding any benefit to this feature. Would be nice to see my calendar and contacts in the UI, but not needed since I have the web client and other connections into that.