Rsync access to the SURBL zone files is available again. If your mail systems are processing more than 250,000 messages per day, then please do not use the public nameservers. Instead, set up rbldnsd and apply for rsync access at:
http://george.surbl.org/rsync-signup.html
(It's also possible to use BIND, but rbldnsd is recommended for being far more efficient at serving list zones.)
If your mail systems are processing fewer than 250,000 messages per day, then please continue to use the public nameservers.