Six post offices will be open Sunday to accommodate Christmas mail.

The U.S. Postal Service announced Friday that the airport, Ala Moana, Kaneohe, Mililani, Waialae-Kahala and Waipahu post offices will be open from 10 a.m. to 2 p.m. Sunday.

Postal officials expect Dec. 18-24 to be the busiest mailing week of the year, with more than 3 billion pieces of mail expected to be processed nationwide. The postal service expects to process and deliver approximately 15 billion pieces of mail and 850 million packages between Thanksgiving and Christmas this year.