KJV:
And he wrote in the king Ahasuerus' name, and sealed it with the king's ring, and sent letters by posts on horseback, and riders on mules, camels, and young dromedaries:
NASB:
He wrote in the name of King Ahasuerus, and sealed it with the king's signet ring, and sent letters by couriers on horses, riding on steeds sired by the royal stud.