My incoming email was unusually quiet yesterday morning. Great, I thought, I’ll get some work done!

However, later in the morning I realised that anyone tryint to send me email was receiving the following error:

PERM_FAILURE: SMTP Error (state 14): 550 Email blocked by ORDB – to unblock see http://www.example.com/

A quick chat with a few people, including Ross of Rozmic (providers of EmailCLoud – my upstream anti-spam solution) and some Googling told me that my mailserver was mis-configured.

ORDB were one of a number of free blacklists of email spammers. Mailservers could query incoming email against their blacklist and accept or reject email based on the response. However ORDB shut down in 2006.

My mailserver was setup in 2007 but still had a configuration whereby it checked all incoming mail against ORDB (or tried).

Recently, it seems, the blacklist servers were reconfigured to list every ip address as spammers. This was probably to get mailserver admins to once and for-all remove references to ORDB from their config!

When I realised this was where the problem was I went to my mailserver configuration file (Exim.conf), found the following lines:

# deny using ordb
deny message = Email blocked by ORDB - to unblock see http://www.example.com/
# only for domains that do want to be tested against RBLs
domains = +use_rbl_domains
dnslists = relays.ordb.org

and deleted them.

Sure enough the mail started flowing once more. If you tried to email me in the last couple of days and couldn’t get through, apologies – please do try again.