And it's been a failure, for a number of reasons:
- it cost a fortune to deploy
- one message costs an equivalent of about 1 USD, which means no one uses it except for communicating with the government
- it relies on a proprietary (although free as beer) rather obscure application for Windows, fortunately a non-profit foundation later developed a cross-platform library for accessing the mailbox
- once you register into the system, any official letter you get is automatically considered delivered, so you cannot deny receiving it, that's why any sane lawyer will discourage from getting such an account ever unless you are obligated to
Obviously, because so much money already burnt, the mailbox system is here to stay.