A client called with a a problem relating to a Mercury mail server that had started to display errors relating to mail being blocked – specifically “Host Blocked by ORDB Rejecting Message” on the mercury console screen.
Initially I thought the client had been blacklisted but then remembered that Mercury had the ORDB server as the default setting on installation. I wondered if the server was blocking all mail sent externally if it was listed in ORDB and was using ORDB for the list of blacklisted servers !!!
However the problem was much simpler and this information explained a lot
On the December 18, 2006, the DNS blacklist ORDB.org has been shut down. As of March 25, 2007, ORDB.org started confirming all requests done to the blacklist, which will result in the incorrect blocking of emails.
So if any of your blacklisting depends on this you need to select alternative servers ASAP !!
In the case of Mercury you can remove the ORDB entry or add another in its place….. you’ll find the setting in Mercury under configuration, mercurys smtp server, spam control