Whatever the case, you will need to find out more information. That is exactly what you should do. In some cases, only a Post Office Box may be supplied. We suggest you think very carefully before sending information about yourself to an unknown person at a Post Office Box. Anyone who claims to be able to get you a job by charging you is probably only after your money for themselves.
Some ads appear to offer jobs.
But the aim of most of these is also just to sell products. Try to get as much information as possible about the actual duties of the position. For most people, these ads can mean low pay, or no pay, and long hours. The ad may look like it's calling for job applicants -e. Really, they just want you to pay for a course.