SACRAMENTO (CBS13) – Post offices are preparing for the holiday rush. Monday and Tuesday are projected to be the busiest mailing days of the year.

A total of $16.5 billion pieces of mail will be shipped nationwide this holiday season. Local post offices kept their doors open on Sunday to help customers get their gifts sent in time for Christmas and many customers took advantage.

“I thought it was going to be crazy,” said a customer.

“This is great; I love it,” said a customer.

“No traffic, no lines, in and out it was great,” said a customer.

If you want your package to arrive in time for Christmas, here are the deadlines to look out for. Tuesday is the cut off to mail First Class packages. And if you plan to mail Priority the deadline is Wednesday. For Express Mail you’ll need to ship by Thursday.