Because of massive registering of bot/spam accounts you will not be able to register an account using one of the following email providers:

yahoo.co.uk
yahoo.com
yahoo.in
ymail.com
hotmail.com
gmail.com
googlemail.com
mail.com
aol.com

More might be added if i see the need, sorry about that, but its really out of my hands and rather in the hands of these email providers making it to easy to register email accounts.