Thanks for posting this, Eric. It's not one I have listed in my antispam document. We vetted the possibility over a year ago and decided against it at that time.
Others, who may be using, rbl.orbitrbl.com, should discontinue using the RBL as soon as possible.
Phonr: (773) 491-9019
Phone: (224) 444-0169
E-Mail and DNS Security Specialist
Network Security Specialist
Customer Service Portal: https://portal.chicagonettech.com
Security Blog: http://networkbastion.blogspot.com/
Web and E-Mail Hosting, E-Mail Security and Consulting