If the mailman comes knocking at your door on Sunday over the next few weeks, don’t worry, he’s not bringing more pizza coupons or the umpteenth credit card offer.

Chances are he’s delivering your holiday big-screen TV or the latest must-have children’s toy.

To meet America’s insatiable desire for instant gratification, everybody’s getting into the rapid delivery game. That includes the U.S. Postal Service, which has added Sunday service in some places, ride-sharing services like Uber, start ups such as grocery deliverer Instacart and traditional taxi companies.

Atlanta also could be soon be on the list for same-day delivery from the likes of Google, Amazon and the newest players in the field — spirits-related businesses such as Drizly, Ultra and Minibar that promise to bring your favorite alcoholic beverages right to your door.

Big box retailers are getting involved, too. Macy’s and Target have rolled out same-delivery in a handful of cities (Atlanta is not yet on the list) while Walmart is studying a similar plan that would involve almost everything it sells, including food, delivered to customers’ homes. The retailers would use contractors to take items from a store to your house.

And the specter of drone-delivery — an idea pitched for the future by Amazon CEO Jeff Bezos — still hangs in the air.

Thank the internet and online shopping. As more Americans eschew traditional shopping in brick-and-mortar stores, retailers, both physical and online, are making it easier for consumers to get purchases delivered when and how they want them.

But there are challenges. Same-day delivery is not cheap, costing anywhere from $5 to $20 and sometimes more, depending on the package. And logistics companies such as Fed-Ex and Sandy Springs-based UPS learned the hard way last year that it’s easy to over promise what can be delivered.

Both were heavily criticized for failures to deliver packages on time. A rash of last-minute orders just before Christmas overwhelmed their ability to meet demand, causing packages to come after the holidays.

UPS said recently it is better prepared to handle this year’s holiday surge. The company has increased capacity, improved technology and sought help from retailers by asking them to offer deals earlier to avoid last-minute orders. The company also warned online retailers that it may charge more this year for 11th-hour orders in some circumstances, such as gifts that require extra capacity.

Retailers need to keep customer expectations realistic, warned Scott Fenwick, a senior director at Atlanta-based logistics consultant Manhattan Associates. The explosion of e-commerce has given consumers more choices, making it easier to seek alternatives if a merchant lets them down on delivery.

“A negative experience can be very serious and very public these days because of social media,” he said.

Business this holiday season is expected to be robust. Holiday sales this year are forecast to reach $616.9 billion, a 4.1 percent increase over last year, according to The National Retail Federation.

Online sales will make up 14.1 percent of total consumer spending this holiday, said Chris Christopher, an economist with IHS Global Insight.

The U.S Postal Service said it expects package business to rise 12 percent this holiday season — between 450 to 470 million packages — because of delivery demand.

Brick-and-mortar retailers also are offering an alternative to delivery — in-store pick up. Customers can order packages online and have their merchandise waiting for them when they come in.

Target said in-store pick up makes up close to 15 percent of Target.com sales.

“About 80 percent of orders are ready for pickup within one hour,” said Antoine LaFromboise, a Target spokesperson.

Making in-store pick up successful requires a delicate balancing act, said Richard Michalec, assistant vice president of consumer strategy at researcher 1010data. Retailers must have enough stock in stores to satisfy both the online shopper whose is coming to pick up merchandise and the customer already there looking for the same item.

“I think convenience is beginning to trump price,” Michalec said, noting that consumers are willing to pay a reasonable premium for product availability and a positive shopping experience.

Craig Menear, chief executive officer of The Home Depot, said the company merged its online and store inventory teams last year to avoid any inconsistencies in what is on shelves and what the Atlanta home improvement giant’s website says is in-stock. About 40 percent on Home Depot’s online purchases are picked up in stores, Menear said.

“We do constant feeds to homedepot.com,” Menear said, adding that the visibility helps make sure both the casual and online shopper find a solid supply of items.