HistoryKat U.S. Postal Records includes a neat book that I had never seen before: Index to Names, Aliases, and Histories of Postal Offenders. It was originally printed by the United States Post Office Department in 1926.
The screen shot in this entry shows part of the title page of this book, which has been filmed and is also available online at Historykat.
The example taken from the introduction indicates the interpretation of one entry. Of course there may be additional records on this person if they were prosecuted, particularly court or newspaper records. And chances are, if they are on this list there was prosecution.