Ever wonder what’s going to come in that mail today? Will you get your sister’s wedding invitation? Is this the day your IRS refund check finally arrives?

Informed Delivery, a free service from the U.S. Postal Service, lets you see what will be in your mailbox that day. Sign up and you’ll receive an email each morning with actual size black and white images of the front side of the letters and cards to be delivered.

Informed Delivery, a new and free service from the Post Office, lets you see what will be in your mailbox that day. usps.com

Knowing when that check really is “in the mail” could change how you plan your day. You might want to get home in time to deposit it.

The service has been available in Northern Virginia since 2014. The pilot program was later expanded to parts of California, Connecticut, Maryland, New York, Virginia, and Washington, D.C.

Bob Dixon, the executive program director for Informed Delivery, told NBC News the feedback was “tremendously positive,” so it’s being rolled out nationally in mid-April. A USPS survey found that nine out of 10 people who signed up for the service checked their Informed Delivery notifications every day.

What's in the Mail?

Feedback from the pilot program showed that Informed Delivery was popular with people who had roommates. This way, everyone in the household knows what they should expect that day, no matter who goes to the mailbox.

It’s also been a hit with people who travel and want to know what’s in their mail, even if they can’t physically retrieve those letters.

Christopher Ebert is CEO of Ophelia Myth Media, which is based in New York and London, so he is always on the go. He’s used Informed Delivery for about two years and likes the way it helps him stay more aware and more in control.

“My life is largely digital,” he wrote NBC News in an email. “Having the ability to see my mail deliveries right on my phone keeps me connected.”

Integrating the physical and digital is a smart move, according to Miro Copic, a marketing professor at San Diego State University.

“This makes postal mail more interesting to millennials, who are on their devices all day long,” Copic said. “And it just might change the equation of how millennials think about the post office longer term.”

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

A Few Specifics

Informed Delivery is for residential mail customers and you must sign up for it at InformedDelivery.USPS.com. It is not currently available for mail delivered to P.O. boxes.

Only 10 images will be sent via the daily email notification. If you receive more than 10 pieces of first-class mail, you’ll get 10 images and a link to see the rest. These images are available for seven days.

Notifications are sent Monday through Saturday on days that mail is processed. If for some reason a piece of mail is not handled via automation, an image cannot be sent.

The Postal Service does not open any mail. This is simply a digital scan of the address side of the envelope. And those images will only be emailed to the person to whom the letter was sent.

If all the mail in one household is delivered to one mailbox, those who share the residence and the mailbox will receive the same images for all the mail delivered to that household.

If you get an image of a letter, but not the physical piece itself, Informed Delivery makes it easy to report that missing mail to the Postal Service. The image can help speed up the process of finding what’s missing.

Why Give Snail Mail a Digital Twist?

In a world of instant communication, the U.S. Postal Service is searching for ways to remain relevant and increase revenue. Mail volume has dropped dramatically during the last 10 years. USPS reports that it handled 61.2 billion pieces of first class mail in 2016, down from 98 billion in 2006.

Informed Delivery gives it a way to reach the growing number of Americans who’ve shifted to digital communications.

“Our emerging consumers, younger folks, are digital natives. That’s how their communications are coming to them,” Dixon said. “We also know that if we can get those folks to the mailbox, they’ll spend longer with each piece of mail than someone who has a long history of mail usage. So the benefit to us is that we continue the relevance of mail in a very digital world and we provide access to the consumers for those mail pieces.”

This scanning technology has been in place since the 1990s. It’s part of the automation process that sorts the mail. This is a way for USPS to leverage something it’s already doing. This digital presence also gives the Postal Service a way to deliver digital advertising. For now, it will be a free bonus for companies that use the mail.

Prof. Copic thinks the Postal Service has found a way to add value for both mail customers and potential advertisers by offering something that no other service provides.

“It’s an opportunity for the Post Office to work with marketers to make their offers more appealing and interesting and to reduce the decline of mail being delivered,” he said. “It opens an opportunity that allows them to play with the big boys in direct marketing, rather than being on the sidelines.”

USPS policy will strictly limit that advertising. It must be related to a piece of mail sent to you that day. For example: If you’re getting a frequent flier statement, the airline could have a link for a special offer sent to you along with the image of their envelope. But you’ll never see an ad for something that’s not already a physical piece of mail in your mailbox, USPS assures customers.

“We don’t want to create spam,” Dixon told NBC News. “We don’t want to create a channel that’s got a lot of noise in it for consumers. Physical mail cuts through the digital clutter and we don’t want to add digital clutter to this channel.”

Security Implications

Mail theft is a serious problem. It’s one of the common ways identity thieves get personally identifying information to commit their crimes. Informed Delivery can help you spot a problem in real time.

If an important piece of mail that was supposed to be delivered isn’t in the mailbox — a credit card bill, tax document or financial statement — you can assume it was stolen or delivered to the wrong address and start working to find out what happened. With identity theft, the quicker you discover a problem, the faster you can move to manage the damage.

These email notifications can be a double-edged sword, cautioned Adam Levin, co-founder of the digital security firm CyberScout.

“If your account is compromised, criminals will know when something of value that they can cash, charge or use for the purpose of exploiting your identity is coming to your mailbox and be there to grab it before you do,” Levin told NBC News. “That’s why it’s imperative that you use a long and strong password for a service like this. It also needs to be a unique password that you don’t share or use for any other websites.”

Herb Weisbaum is The ConsumerMan. Follow him on Facebook and Twitter or visit The ConsumerMan website.