You may not acquire items (kinyan) on Jewish festivals unless they are needed for that Jewish festival or for a mitzva. The classic example is bringing food or wine to a house for Jewish festival lunch, which the house owner acquires on the Jewish festival for the Jewish festival. Other permissible kinyan on Jewish festivals is giving:

• Siddur, machzor, or chumash to use on that day.
• Permissible medicine for use on that day. 

On bringing mail or a newspaper into your house on Jewish festivals, see Jewish Festivals: Bringing Mail inside House  and Jewish Festivals: Bringing Newspaper inside House.