CHICAGO (CBS)– In order to ensure your packages are delivered by Christmas, the U.S. Postal Service announced holiday mailing deadlines.

From Thanksgiving up until New Year’s Day, the Postal Service said they expect to deliver more than 900 million packages and nearly 15 billion pieces of mail.

The Postal Service provided guidelines to ensure mail arrives by Dec. 25.

For packages to the military (APO/FPO/DPO), zip code 093 only, the deadline for Priority and First-Class mail is Dec. 4.

For packages to the military (APO/FPO/DPO), all other zip codes, the deadline for Priority and First-Class mail is Dec. 11. Dec. 18 for USPS Priority Mail Express for (APO/FPO/DPO) for all zip codes except 093.

Dec. 14 is the deadline for UPS Retail Ground.

December 20 is the recommended deadline for First-Class mail (including greeting cards) and First-Class packages (up to 15.99 ounces).

Priority Mail Express’s recommended deadline Dec. 22.