How can you find out if you are about to be issued a traffic ticket in Illinois via mail?

Since it is unknown to you if he was running active radar or not, it will be difficult. You could try calling the court jurisdiction in the area where you believe you went through, and ask there Court clerk to see if they received anything from that Trooper. Alot of times you will see Law Enforcement stationed at constructions zones to just reduce the speeds of cars, but actually not running radar to giving tickets. Although, nothing says that a ticket isn't in the mail, but it usually comes so you have to sign for it.