After several gripping opening pages in which Dane Thorson, assistant cargo master of a free trader spaceship, awakes from attempted poisoning in unknown surroundings, [Postmarked the Stars] lapses into standard cosmic cops and robbers…. There's less to the plot than meets the eye, as the last half of the book consists mainly of repetitive captures and escapes; also, the characterizations, dull and two-dimensional, do not live up to the standards of Miss Norton's other books. This book is not likely to win her new readers, and will only disappoint her many fans. (p. 1947)

Margaret A. Dorsey, in School Library Journal (reprinted from the May, 1970 issue of School Library Journal, published by R. R. Bowker Co. A Xerox Corporation: copyright © 1970), May, 1970.