With respect to the huge amount of letters having survived, written by Max Reger as untiring self-promoter, but also with respect to its impulsive rather than literary nature, a complete edition of Reger’s letters is currently impracticable. The edition of chosen correspondence, especially with his publishers, (see Publications), hence was a kind of compromise very much welcomed by musicologists and conoisseurs alike, to be continued well into the future. Still, it is highly desirable for musicological research to have a complete assessment of all of Reger’s letter, to document his everyday life, the creative process, success or failure of plans, performances, questions of interpretation and in some cases also aesthetic views expressed by Reger. The assessment of the letters with respect to the genesis of compositions was an essential precondition for the Reger Thematic Catalogue. Furthermore the compilation of all currently known postal items, complete with original holograph location, date, addressee, and excerpted content will offer Reger scholars the opportunity of detailed enquiries with respect to their individual research.