I’m an international student from Poland and I have just received a letter of recommendation from my US Host family, in PDF with their signatures hand-signed, so it looks official and would be hard for me to falsify. It is an absolute gem and in my opinion would present me from a unique perspective not included in other recommendation letters. Will it be a bad idea to send it to the admission offices via e-mail? My thinking is, that they either ignore it - no change or take it - benefit. Can it hurt my chances in any way? [can AO be like - oh he is oversending stuff, lets reject him] or is there no risk in doing that?
Does this new rec shed some new light on you as a person? Does it inlcude new, different information that is not in your other letters of rec? If so, go ahead and send it but check first that the college you are sending it allows extra recommendations. Do not exceed the number of supplemental materials they will consider. Make it clear in your email that it is an extra recommendation, and not one included in the original app or sent by your school.
Another consideration is that some colleges really only want letters from someone like a teacher who has seen you in an academic setting over at least an entire course. Others say that they are OK with ones from a coach or music teacher or supervisor at a volunteer organization or job who knows you very well. Others are more vague in what is acceptable.
I’d look at the college’s website to see what kind of letters they want to get, and if they are OK with extra letters in general. If they seem fairly strict about what they what, I wouldn’t send it. If they aren’t that strict, sending it might help a little.