Trying to get connected to Zimbra GAL over LDAP from the Public Internet through a Firewall using MAP/NAT to private internal IP network. Can access using Thunderbird on a client local to Zimbra server but not on the other side of the firewall.

Enabled the correct 389 port mapping etc but no joy, even tried opening the IP target address completely to a known IP range but still the same result. Is there a permissions issue somewhere in Zimbra? Something like the hosts.allow file or a slapd conf entry? Probably something obvious and silly but I am generally good at trying the obvious and silly things...

Help much appreciated ;-)