zen.spamhaus.org RBL

[uxbod]

Just remember with any free RBL a constraint of the service is how many lookups you are performing ... too many and you will be classed as a commercial service which will incur a charge.

[jones0610]

Understood and thanks for the reminder. My volumes are quite low (less the unsolicited spam that I get because I registered my domain name over 15 years ago) so I think there won't be any issues with the various providers that I use.. Projects like Spamhaus do monitor usage and will tell you if you need to upgrade.

[uxbod]

I am low volume; run a caching DNS server; plus upstream. Perhaps your upstream is making to many queries ?

[jones0610]

Looks like using OpenDNS resolved this. Spamhaus test says:

{snip}
554 5.7.1 Service unavailable; Client host [192.203.178.107] blocked using zen.spamhaus.org; http://www.spamhaus.org/SBL/sbl.lasso?query=SBL230
Terminating conversation

I raised the issue with my ISP but thaty haven't gotten back to me. My caching DNS server uses my ISP name servers to forward to so I'll need to see what's involved in going to OpenDNS assuming that they are going to be mega-reliable moving forward.

[ArcaneMagus]

I have never once had a problem with OpenDNS in the year or so I have been using them. Their system status can be found here OpenDNS > System (also available at http://208.69.38.170/). Any problems with a data center cause traffic to be re-routed to the nearest center. I would say that any system that handles 19+ billion queries a day would have to be pretty reliable

For BIND you just need to change the forwarders directive.