Seiffert was born in Beeskow an der Spree, Germany, and died in Schleswig, Germany. He was first educated at the Joachimsthal Gymnasium at Berlin, and then at the University of Berlin where he received a Ph.D. in 1891 for the dissertation J. P. Sweelinck und seine direkten deutschen Schüler.
- Making piano transcriptions of some of Bach's works (in association with Max Schneider).
- Assisting with the editing of the Händel-Gesellschaft.
- The New Grove Dictionary of Music and Musicians. London: Macmillan Publishers, 1980.
- gfhandel.org – editions Archived 2007-03-10 at the Wayback Machine
- Ernst Klee: Das Kulturlexikon zum Dritten Reich. Wer war was vor und nach 1945. S. Fischer, Frankfurt am Main 2007, S. 566.