Sometimes I get emails like the following, presumably targeted to me as a friend/contact of some person, X:
You have a message from X on our super awesome website! Click here to read this message.
where, if you click on the link, you are prompted to register an account on the super awesome website in order to read the "message" from X.
Is there a name for this practice of getting users to register by holding a piece of individually targeted content hostage?
Another example is the way some websites will tell you,
Five users have been searching for you on this site, register to find out who.