Santa Post Christmas Seals are well documented commercial Christmas Seals. Larry Hixon was a Pioneer collector of this material. His collection was well documented by Joseph Ward, jr. In, Larry Hixon's Santa Post, published by CS&CSS and offered on the Literature page of this website.
This image, submitted by advanced tied on collector, George Lukacs, is an important clue in their history. Now I must read the book to see just what Joe and Larry knew or supposed about the Santa Post series.