UCE has added RBL listing with a superset of network we use for relaying outgoing emails sent by ExchangeDefender customers. The RBL listing is classified as an ISP block, which generally will take out the entire assigned netblock. In this case, the block is against one of our data centers netblocks which includes the outbound network we use in Dallas (174.136.31.16/28)
The block should automatically remove itself. We will continue to monitor the listing and its impact.