Last year Catholic High School in Little Rock, Arkansas generated a great deal of online discussion, debate, support and dismay over a sign in their Front Office. The sign said 
 "If you are dropping off your son's lunch, books, homework, equipment etc, please TURN AROUND and exit the building. Your son will learn to problem-solve in your absence."

The sign wasn’t in response to annoyed Front Office staff being overworked and distracted.  Rather the “all-boys private school in Little Rock has long had a rule barring parents from coming to the school to drop things off - such as forgotten lunches, assignments and sports equipment - for their children, but parents occasionally forgot about it and had to be turned away at the front door.”

Now that the media response has quietened down I wonder if your school executive had any response? My office at a Preschool to Year 12 school is near the front office so I often hear parents dropping off forgotten items. However this school has a policy of encouraging, expecting and wanting parents to be involved and in partnership with the school. The discussion over this sign did however mean we decided for now not to introduce a clever system which would have sent text messages directly to a parent when an item was placed in lost property.