We have received several reports this morning about our IP address blocks being on Verizon’s RBL. The following errors were given to some of our customers on ExchangeDefender:

outbound1.exchangedefender.com #5.5.0 SMTP; 571 Email from is currently blocked by Verizon Online’s anti-spam system. The email sender or Email Service Provider may visit http://www.verizon.net/whitelist and request removal of the block.>

In our calls and discussions with Verizon we have received a confirmation that we are not and have not been on their RBL. At this point the mail is routing correctly so we are just chalking this up to there being a temporary glitch with Verizon’s RBL systems.