For uneducated gangsters, problems are “sorted”, as you may have heard in the films such as Al Capone. As a result of such films, another abomination (cosa terrible) has entered the English language, and perhaps some people think it is fashionable to imitate villains (imitar maleantes). The reality is that it is wrong to use sorted on its own.
The correct use of “sorted” is with the preposition “out”. “Sorted out” is a phrasal verb (verbo con preposición). Therefore, problems are sorted out, the mail is sorted out by the Post Office and the pens were sorted out by the English teacher.
Please also note that one can only sort out things that are plural – you cannot sort out one problem. So if you were to say that “the economy in Spain has been sorted out” then you have made an error. The correct way to say this would be “the problems with the economy in Spain have been sorted out”.