Thanks to MusicProf78 for the Youtube
I’m Gonna Sit Right Down And Write Myself A Letter was composed by Fred E Ahlert, Lyrics by Joe Young. Fats Waller recorded this cut May 8, 1935. It was the first recording of the song and it was at the height of Fats’s popularity. His group Rhythm on that date included Herman Autrey,, trumpet; Rudy Powell, reeds; Al Casey, guitar; Charles Turner, bass; Harry Dial, drums; and Fats, piano and vocal. It was a very popular record and others followed in his recording footsteps.