I always sent my stuff "return receipt." When I received the little green card back in the mail, I knew someone had signed for my stuff. Maybe it gave me a false sense of security, but I did feel better once the card came back. The only problem I had with my application was that they had filed some of my transcripts by my maiden name (even though I listed my maiden name on my app in the appropriate space), and I did have to call and make them look under my old last name. If I were depending on someone else to send something, I contacted the responsible party (ie. for health professions letter, transcripts, etc.) directly to see if they'd sent it and on what date. No one I knew had significant problems with the application center (out of about 30 applicants I knew). After my file was complete, which was late July inlcuding transcripts, recs, etc., I received interview invitations for September 3 (even though I took the August MCAT!). Does that make you feel better?
P.S. I recall that the website was updated before I received the confirmation from the TMDSAS...the mail notification was pretty slow.
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We are the music makers, and we are the dreamers of the dreams.
--Willy Wonka