Shoutbox

The whole reason why Microsoft has put in such an effort with creating these preventions is so as you cannot invade the privacy of others.  If someone has blocked you then there probably s a good reason behind it and if you have a problem with them blocking you or would like to know, then try emailing them?  Going behind there back will only intensify the situation and make things worse (no matter if they unblock you or not).

The best method in my opinion, is not to need a block checker and try not to get people offside.

This script could work, but how do you suppose it tests to see if your contacts have this script enabled?  There are a number of flaws anyway.  Good idea, but not entirely practical.