HOW TO DETECT A PERSON blackmailer
Normally the blackmailer person begins with the request, the request (malformed) le cover a necessity.
When you want something, ask you directly rather than seek ways to make you feel guilty for you offer to do ,.
Should not fall, apply the law of ice, but if it is a social network, is tedious, because you're always waiting for you to answer something, so what better to do is block that person for an indefinite period.
The best thing you can do is to keep the people blackmailers distance, because once they enter your life will be difficult to send them through a tube, eggs for this steel requires mine.