If it’s a fit for him, I hope your son applies to Yale, because it’s a wonderful school. The letter he got has served its purpose if it made him consider doing so. You will probably receive an avalanche of letters from UChicago; see if they still send a “free” T-shirt 
Having looked at the postage and printing costs of this marketing material, I have to marvel at the wasted resources. Today’s kids are as likely to read an email as a printed brochure, and the costs (financial and ecological) are very different. Snail mail should be reserved for T-shirts :)).
DS still (as a college sophomore) gets marketing materials. The schools are not suitable for a transfer school, and you have to wonder about the school’s list culling software. My sympathies are extended to the hapless school that sends out letters with glaring grammatical errors.
We created a new email account just for college marketing. It might be too late for you, but I recommend it, and doing so before the next round of testing might keep your mail lady’s knees from buckling under the load.
Good luck to you and your son.