Noel Jones: > Guy wrote: > > Hi guys, > > > > I had a problem earlier today when our local DNS server's forwarding > > servers were slow to respond. > > > > I had a number of emails from various sources rejected as blocked by > > zen.spamhaus.org. The IPs I checked weren't on the list according to > > the spamhaus website. > > No, this is false. Postfix will log a warning and pass the > mail when an RBL query times out.
He was using "reject_RHSBL_client zen.spamhaus.org". I speculate that his ISP was making some money by redirecting non-existent name lookups. Usually such ISPs are smart enough not to do this with reject_RBL_client lookups. Wietse