When blacklisting spammers via Postfix it would be nice to add it once to all servers, and a resync when we add more servers. Could also be usable for whitelist.
One thought related to your feature request is that you can create a dns based blacklist for domains (not for individual email addresses as easily) and set all your servers to use that rbl. The performance difference would be negligible on small systems, but it would be more efficient (dns query vs db query) and is available as a solution today. On a related note, having a new black/whitelist type that accepts domain names and maintains a dns rbl might be worth a feature request of its own.
That sounds like a good feature if its easy in ISPconfig. Im not sure its good if you need to manually have it up to date via Bind directly, too much time to write the zone files.
