Graywolf Press has published Airmail: The Letters of Robert Bly and Tomas Tranströmer, edited by Thomas R. Smith. This edition of the correspondence is larger and more inclusive than the volume that appeared in Swedish with the title Air Mail from Bonniers in 2001. Torbjörn Schmidt edited the Swedish edition, which contained 199 letters, most written in English and translated into Swedish by Lars-Håkan Svensson. By the time the Graywolf edition was ready—an event that had to wait until Tranströmer had guaranteed an English-speaking audience by winning the Nobel Prize for Literature in 2011—nearly a hundred more letters had come to light, and could be included.
Tranströmer wrote the first three dozen letters to Bly in Swedish, before shifting over to English for the remainder of the correspondence. These Swedish letters, and snippets of others, have been translated into English by Judith Moffett and Lars-Håkan Svensson. The book is available from Graywolf in both hardcover and e-book formats.