I'll give you an example. An Officer may be working a road construction traffic detail and observe a vehicle drive by with an expired or rejected inspection sticker. The Officer would most likely not be in a position to stop this vehicle once it passed because (a) most construction details do not have a marked police vehicle assigned but a Police Officer on foot directing traffic or (b) it may not be safe to stop the vehicle at this time due to traffic conditions with construction. The Officer is in a position to record the vehicle plate, make, model and color of vehicle along with the date/time and location. When the Officer is working his next shift, a computer check thru the RMV will confirm if the inspection sticker is expired or rejected for more than 60 days due to emission failure. The Officer would then issue the registered owner a motor vehicle traffic citation and on the citation itself, there is a box to check off for mailed to violator, and put the citation in the mail. This is one circumstance when a citation maybe sent in the mail, another may include an Officer crossing children on a school traffic post and not able to stop a vehicle. Generally, when an Officer is not in a position to conduct a motor vehicle stop but can record the information and verify there is a violation, a motor vehicle citation will be mailed to the registered owner of the vehicle.