This series contains letters received by John Held, Jr. from mail artists around the world. A document entitled "Key to the Collection" in Box 1, Folder 26 contains brief biographies, descriptions of artistic style, and a history of Held's correspondence with each artist.

Correspondents are from 44 countries in South America, North America, Europe, East Asia, Southeast Asia, the Middle East, Australia, Africa, and the Caribbean. Much of this correspondence includes mail art letters, envelopes, postcards, artistamps, photocopy art, collage, and rubberstamp art. Artists include: Mark Bloch, Hans Braumüller, Jean Brown, William Gaglione (a.k.a. Picasso Gaglione), Dick Higgins, Ray Johnson, Shozo Shimamoto, Ryosuke Cohen, Michael Leigh, Guglielmo Cavellini, and Rod Summers. There are also scattered letters from Carl Andre and Clement Greenberg.

Printouts of correspondence sent by Held include letters to international art institutions, artists, mail art collectors, archivists and librarians, journalists, and media publications regarding mail art, exhibitions, performance art, travel planning and print publications. There is also a file of letters between Held and artist/editor Steve Durland.

Letters are arranged by country and alphabetically by correspondent thereafter. Letters sent by John Held, Jr. are at the end of the series.

This series has been scanned in its entirety.