I have a good “other recommender” for the common app (not teacher/counselor). I do not see a place on Princeton’s recommendation section in which you can use an “other recommender”. Will I really have to ask my recommender to snail mail her recommendation to Princeton? Lots of other schools don’t have this section, but I have noticed that Harvard and Stanford do. All advice is welcome.
Very much a newbie here, but my son was accepted SCEA and he did have the supplemental person mail it in an actual envelope. 
And he called to confirm it was received, about a week later. Make sure to have the recommender label your full name, birth date, school, etc. on it.
Does it seem like an applicant ought to let the school know additional recommendations are coming, since the Common Ap only allows 2 academic ones for Princeton? If so, what would be the best way to let them know, email to the admissions office?
I think I might post this question as a separate thread.