PIERRE, S.D. (DRG News) – The U.S. Postal Service expects this week to be their busiest week of the holiday mailing and shipping season.

They predict today (Dec. 16) will be the busiest day for usps.com, with more than 8.5 million visitors expected to use the website for help shipping holiday gifts. This week alone, the Postal Service expects to process and deliver nearly 2.5 billion pieces of mail and packages.

New this year, mail and packages weighing more than 10 ounces and/or are more than a half-inch thick using stamps as postage cannot be dropped into a collection box or left for a carrier to pick up. Take them to a window clerk at a Post Office. Click-N-Ship customers are unaffected by this change.

Overall, the Postal Service anticipates delivering 800 million packages between Thanksgiving and New Year’s Day.

The Postal Service also offers shipping tips in 10 video “how to” guides. Each video is less than three minutes long and shows how to address packages, ship packages and pack a box so items arrive safely.