It’s D-Day at the post office. Workers are braced to carry more than 725 million pieces of mail today, the busiest delivery day of the postal year.

That’s a 25 percent increase over a normal weekday’s mail.

Mail pouches will be bulging with Christmas cards, letters and packages dropped off at post offices around the country on Monday, the busiest mailing day.

A record 285 million cards and letters were postmarked Monday, compared with 280 million on last year’s busiest day, the Postal Service said.

Those figures don’t include packages, which also are at their peak, or advertising mail.

“Over the weekend, everybody gets busy wrapping their gifts and writing their cards, and Monday is the day they all run into the post office to mail them,” said spokeswoman Sandra Harding.