Instead, Earth Class Mail is a service that has been in business since 2006 and they operate within the existing legal framework of mail: they are effectively the kind of service that is required to live in an RV, where a third-party receives your mail on your behalf. To make this work, you sign forms from the post office that you send to Earth Class Mail, which are then kept on file to demonstrate they can legally open your mail. Maybe Outbox used the same process, maybe they didn't, but this article made it sound like Outbox is responsible for this legal framework: wrong, the ability to assign "open my mail" rights has existed for a long time.
Rather than having to have cars driving around attempting to "undeliver" your mail with some ludicrous three-day delay as Outbox did (at extreme cost to the service that calls into question whether their business model would even succeed, a fact mentioned in this article linked today, and limiting them to only even being able to think about operating in high-density regions of the country), you simply have your mail delivered to them. You can initially set this up with your local post office as you work on "moving" to ECM, and you can even do it temporarily if you just want to try it out (the post office will happily forward mail for as little as 15 days: again, this is a use case they actively support).
But frankly it is so amazingly relaxing once you "commit" and outsource your physical address. I have a lot of friends that move every couple years, and the idea that they have to change their address at the same time is silly: that is the most stressful moment to be trying to move mail delivery and you can't usually overlap the old and new addresses to buffer mistakes. In the most extreme situations, people who are traveling a lot (for whatever reason; maybe they have a job that requires them to be in random locations for weeks on end a lot, or maybe they are just kind of nomadic and stay with friends a lot as they travel the country) will tell you to send things to their current location. Outbox sort of helped with this, but the three-day delay sounded really irritating: ECM just solves this problem outright; you don't even need a real physical address at all.
Indeed, I seriously have now switched to using my Earth Class Mail address for everything: my drivers license even has that address on it (and yes, I verified with the people at the California DMV that there was no issue with this, and they technically do have my physical address on file; but their policy is to print the mailing address of the driver on the card), which makes it really easy for me to never get into an argument with anyone about what my address is: I effectively now live at Earth Class Mail in Los Angeles. The only people who know my real address are the US government (DMV and voting registration, though they happily send my voting materials to ECM), the power/cable/phone services to my apartment (again, bills go to ECM), and my health insurance company (they base pricing on where you physically reside).
They offer multiple locations around the country, so you can get an address vaguely near you or opt for one that "looks good" for your purpose (maybe you want your startup to look like it has an office in San Francisco, for example). With some of the addresses they are legitimate "street addresses" that can receive packages on your behalf, and you can either have the package forwarded to you or you can go pick it up from them if you need it now and live near enough to the location. (Though, with packages, I normally just one-off deliver those to my apartment.) (I wonder if you can have them open the package and take a picture of the contents... I never asked ;P.)