Published: Dec 13, 2013 10:50 AM EST

TAMPA Fla.— Some Post Offices in the Suncoast District will deliver packages this Sunday and next Sunday (Dec. 15 and 22). Customers may also notice their letter carriers delivering earlier in the day.

The Sunday and earlier deliveries will take place in ZIP Codes in the Suncoast District that have significant increases in package volume. The Suncoast District includes Post Offices with the first three digits of the ZIP Code beginning with 321, 327, 328, 329, 335, 336, 337, 338, 339, 341, 342, 346 and 347.

These special Sunday deliveries in the Suncoast District are for the holiday season and are not part of the recently announced Amazon Sunday deliveries with the Postal Service that are taking place in Los Angeles and the New York metropolitan areas.

The Postal Service expects to process 545 million pieces of mail every day throughout this holiday season; totaling nearly 15 billion pieces of mail to be delivered between Thanksgiving and New Year’s Eve. Competitive package volume also is expected to increase by approximately 12 percent from last year to about 420 million packages during the 2013 holiday season.

The busiest mailing day this season is projected to be Monday, Dec. 16, when more than 600 million pieces of mail are expected to be processed. The same day, 6 million customers are expected to visit Post Offices nationwide. The busiest delivery day for mail will be Wednesday, Dec. 18 and the busiest day for package delivery will be Thursday, Dec. 19.