I told DD to check "NO" on all those tests -- PSAT, SAT, ACT -- where they asked about personal information, e.g. potential major, sports, gpa, etc., precisely because I did not want to be flooded with email and junk mail. It's a waste of paper and time (to recycle and delete all that stuff), and it's distracting from the process.
Despite her vigilance, DD still got a bunch of junk emails and some junk mail from schools DD has ZERO interest in. Some are still sending emails begging her to apply, waiving the fee, etc. They are doing this because they want their application numbers to go up, that's all.
If your kid has high stats, or even pretty good stats, s/he may get emails from Ivies and more selective schools, also trying to drive up their application numbers, but which have no intention of accepting your kid. It's emails and invitations like that that prompted me to tell DD to check "NO" to every box and not to give any personal information about herself on those tests -- which is the main source of all the junk college email/junk mail.
My advice: help your kid to find the schools s/he wants to go to. Read Petersons, ask your guidance office, visit schools that are nearby, and see what your DC thinks. But make sure the process is directed at least in part by your child's desires, and don't let your DC get distracted by sales pitches from schools. You go to them. That's the best way to find the right fit.
Best of luck to you and your child, OP.