I want to send Georgetown a letter reiterating my interest, how it’s my first choice, and updating them with any new accomplishments, etc. but who should I send it to? Should I email it to the undergrad admissions office or should I mail it?
@screenname3488 I am in the same position. I am considering mailing my letter because I thought it would be more professional seeming that way. But I basically know nothing. Let me know if you learn anything, good luck! 
@ColdCider good luck too! and do you know when you’ll mail it?
Bump
@screenname3488 I applied to Colorado College and got deferred, and in the deferral letter they said they would be reviewing our applications again in early march. So, I am going to wait until mid February to send it so it doesn’t get read, filed, and forgotten. What about you?
@ColdCider I was thinking February too because that’s when they start going over the apps, and I think I saw an old post saying to mail them out in February
Not to dissuade anyone, but Georgetown does not track demonstrated interest (which would include such letters), with the exception of waitlistees.