John Sutherland on Monday addresses a holiday package intended for his younger brother, a Navy reserve stationed in Kuwait. Lines were long most of the day at the post office on Fifth Street. Monday was the busiest mailing day of the year, according to the United States Postal Service. The postal service will deliver 20 billion cards, letters and packages this holiday season. The postal service estimates that 1.6 billion cards, letters and packages were sent on Monday, compared to a national daily average of 670 million. Wednesday is expected to be the busiest delivery day.