This second letter. — It seems to us that the first letter must be that extracted from the king by Esther (Esther 8:8), and consequently this “second letter “is Mordecai’s (Esther 9:20), which is now confirmed in a more authoritative way.
Related Commentaries of Esther 9:29
Esther 9:29
29 Then Esther the queen, the daughter of Abihail, and Mordecai the Jew, wrote with all authority,h to confirm this second letter of Purim.