[Here briefly focus on Sample Letter to Friend about Future Plans. You can follow these sample letter to a friend telling him what you intend on doing after clearing a board examination and how the profession you will further choose can shape up your future career.] Date… Friend’s name…
I believe that the closest synonym for the word overwhelmed is awestruck. It isn't jubilant, because that means happy. And overwhelmed isn't necessarily happy, it is just a strong emotion. Flattered and gracious just don't fit here.