An active deterrence method and system deter rogue cyber activity targeting one or more protected legitimate users (PLUs). Methodologies and/or techniques are included to establish a PLU registry and/or enable a PLU to bear an identifying mark; detect rogue cyber activity; issue warnings to one or more rogue users (RUs) that target or attack PLUs with the detected rogue cyber activity; detect non-complying RUs that ignore or otherwise fail to comply with the warnings; and deploy one or more active deterrence mechanisms against the non-complying RUs. One active deterrence mechanism includes deploying a plurality of scripts to each PLU, and executing the scripts to issue complaints and request the non-complying RUs to clean their mailing lists of all PLUs. Other active deterrence mechanisms include alerting unaware business affiliates of the RUs, and notifying victims or law enforcement authorities of unlawful rogue cyber activity.