Chapter 10 of I Maccabees tells of the competing efforts of Seleucid King Demetrius I Soter and his contender, Alexander I Balas, to win the support of the Jews in Judea. Verses 25b-45 quote a letter, allegedly sent by the king, containing numerous overwhelming promises. Following an accepted view in research, which regards the letter as a fake, this paper raises the possibility that it was written as an ironic text, the irony being at times evident and at others more covert. The article suggests that in the composition of this array of promises, its author consulted, collected, and borrowed elements, even entire clauses from several other, authentic, Seleucid letters sent to the Jews in Judea. Of these letters, the resemblance in content between the text in question and two letters of Antiochus III, quoted by Josephus in book 12 of his Antiquity of the Jews, is especially striking. The apparent reliance on such authentic Seleucid documents, which are not quoted in I Maccabees, indicates that the author of the letter and the author of I Maccabees used the same official Temple archive, and quite likely, are the same person.