Med School Letters of Rec

<p>What is the best way to send Letters of Rec for Med school application?
I have an account with Cal Career center letter service but I heard it is better to have the writer submit directly to AAMC? </p>

<p>If I use the career center letter service can I send the letter from there to AAMC? or do I have to send them individually to each school? In other words does the AAMC take letters from the letter service? I'm asking because some professors don't have the AAMC account so it is easier for them to send it to the career center.</p>