The Howling Mad Mail was a mail art project initiated by Jacob in 1985, reflecting his growing alienation from the mail art community. The compilation of material received was unpublished.
Riding Beggar ceased publication in the 1990s. A complete run of PostHype was acquired by the Museum of Modern Art in 1987. Incomplete sets are held by the Getty Research Institute (acquired with the Jean Brown, Bern Porter, Carlo Pittore, and other people’s papers) and active mail art archives such as the Artpool Art Research Center.
The Riding Beggar archive is housed with the John P. Jacob Papers at the Beinecke Rare Books Library, Yale University.