hesketh.com loves the Internet. That's why we work to make it better. Since its founding in 1995, hesketh.com has grown with the Internet -- the world's most powerful people connector. Our current contribution to making the Internet better is Enemieslist (EL). Trusted by data scientists, security experts, and anti-spam professionals, Enemieslist protects over 3.6 billion users from online abuse. EL works by classifying hostnames (PTR records) in order to allow policy to be applied in various contexts.Originally intended to aid in the risk evaluation of accepting mail from a given host, EL's unique approach and comprehensive coverage now finds applications beyond anti-spam. Our classifications find use in reputation services, anti-fraud, anti-abuse, anti-spam, threat detection, information security, network security, calibration of data sets, and priming machine learning systems.