The United States Postal Service is preparing for the busiest mailing day of the year on Monday, when more than 800 million pieces of mail are expected to enter the system.

This represents a 40 percent increase in the average daily volume of mail the USPS handles.

Monday is the recommended deadline for sending greeting cards and holiday letters to arrive in time for Christmas. The Postal Service says priority mail can be sent on Tuesday and express mail on Wednesday and still make it on time for the holidays.

Customers can also skip the post office altogether and ship their items online using the Postal Service’s website, www.usps.com.

The site allows people to print shipping labels and pay for postage. The USPS will even pick up your packages for free.

The organization says customers looking to save time can also use Automated Postal Centers. The APCs are just like an ATM and act as a virtual, stand-alone Post Office, dispensing stamps, weighing packages and calculating postage.

For more information, you can go to the United States Postal Service website at www.usps.com or call 1-800-ASK-USPS.

Photo Credit: By User Coolcaesar on en.wikipedia [GFDL (<a href="http://www.gnu.org/copyleft/fdl.html" rel="nofollow">http://www.gnu.org/copyleft/fdl.html</a>) or CC-BY-SA-3.0 (www.creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons