On the internet almost everyone asks for your email address. I used to give in good faith and in return I received tons of spam. I am sure it has happened to you too. Here's how you solve it.

Use mailinator.com. The beauty is that now you can use any random email address like john@mailinator.com or jane@mailinator.com (anything at all) and then go to mailinator.com and retrive your emails.

Such emails are visible to everyone if they know the id. If you don't want that then go to mailinator.com where they will provide you with a randomly generated id which you can use like kwzlbwnltdyrn@mailinator.com. The emails for kwzlbwnltdyrn@mailinator.com can then be viewed at http://www.mailinator.com/mailinator/maildir.jsp?email=kwzlbwnltdyrn

BTW: This is called security by obscurity. In this case it is good enough.

If a service provider blocks mailinator then you can use alternative domains like klassmaster.com, sogetthis.com etc.