First, CXBL is received when your IP is blocked because it was seen "exhibiting spam-like behavior". Do you use your email for business or sending a mailing list? Do you use a VPN? Do you send a LOT of mail? Any current/recent malware infections? Just trying to think of common reasons Cox would block your IP.
As for requesting to be unblocked I suggest using a alternate email like Gmail or Yahoo and send to unblock.request@cox.net. Or if possible, use Cox webmail. It breaks downs what information you have to send. Did you have any specific questions about those requests? The domain would be cox.net and the IP/CIDR would be the IPv4 address found at sites like IPchicken.com. Everything else should be self explanatory.