You must have your Original Email to get the update for Free. If you have lost this, then you must purchase the upgrade. This is explained at:
http://www.mtu.com/support/info.htm#Upgrades
There is no email sent out unless we have a Major Upgrade, if your not on the mailing list, then you will not get this. You can always look at:
http://www.mtu.com/support/news.htm to find out what is in the works or what is released.