June 2011: another public variation of the list is available. Similar to the public list described below, but returning results (blocking) only for the status codes provided in the query.
Some examples:
2.0.0.127.2-4.flex.quorum.to. = NXDOMAIN
2.0.0.127.2-4-11.flex.quorum.to. = 127.0.0.11
2.0.0.127.11.flex.quorum.to. = 127.0.0.11
November 2009: the Quorum database can be accessed using industry standard dnsbl query protocol. Configure your mailserver to consult the dnsbl: list.quorum.to.
When a host is allowed, Quorum will return an NXDOMAIN result, as per the industry standard protocol. Because of this Quorum cannot return a link when a host is allowed and mail receivers cannot request that a host's mail be rejected, as they can do when using the plugin-based protocol.
Example of an allowed host:
$ dig 94.43.127.216.list.quorum.to.
; <<>> DiG 9.4.2-P2 <<>> 94.43.127.216.list.quorum.to.
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 13800
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;94.43.127.216.list.quorum.to. IN A
[..]
When a host is rejected, a status code and URL will be returned as per the normal subscription-based operation. The URL should be returned to the rejected SMTP client so that senders can request that their mail be allowed.
Example of blocked host (blocked because it has never been seen to send mail):
$ dig any 4.3.2.1.list.quorum.to.
; <<>> DiG 9.4.2-P2 <<>> any 4.3.2.1.list.quorum.to.
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57998
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;4.3.2.1.list.quorum.to. IN ANY
;; ANSWER SECTION:
4.3.2.1.list.quorum.to. 0 IN A 127.0.0.0
4.3.2.1.list.quorum.to. 0 IN TXT "http://www.quorum.to/q/...(example url)"
[..]
Another difference between the plugin-based protocol and the free public protocol is that new hosts will not be added to the database automatically. Additions may be accomplished by sending a test mail to the quorum smtp server. This proves they exist as routable, non-port-25-blocked senders. The rejection url provided to such new hosts has instructions.