You have received a notice in the mail for failing to stop at a red light or for failing to come to a complete stop when making a legal right turn on red (Illinois Vehicle Code Section 11-306).
As stated in the Illinois Rules of the Road Chapter 8 - Traffic Signals and Pavement Markings reads: "RED LIGHT, stop at the marked stop line. If there is not a marked stop line, stop before entering the crosswalk. If there is no crosswalk, stop before entering the intersection. Do not go until the light is green and the intersection is clear. You may make a right turn at a red light but drivers must come to a COMPLETE STOP and yield the right-of-way to oncoming traffic."