Dear Dr. Smith,
Thank you very much for agreeing to write a letter of
recommendation for me. I've appreciated your help all the
more since I learned how busy you would be at the end of
the term. I am enclosing a stamped envelope addressed to
the graduate school of the university so that you can just
drop your letter in mail. I will let you know at once ifget the
scholarship.
Thanks again for all your kind support and understanding.
Yours sincerely,