mod_pubsub_serverinfo: Warm-up opt-in cache By warming up the cache that contains the opt-in data, the first publication has a better chance of including domain names for remote domains that opt-in. Without this change, those domains are named only after the _second_ publication, which can take a while. New users are likely thrown off by that.

Introduction
============

This module checks the IP address of newly registered users against a
DNS block list. If a positive match is found, it gets logged.

Configuration
=============

  Option              Type     Default
  ------------------- -------- ------------
  registration\_rbl   string   *Required*