Problem with registration message

[mr.fifteen]

Hello!
first thing... sorry for my english...
i use virtuemart 2.6.16 and Joomla 2.5.20 and this is my site http://www.utetmedshop.it
when i register i receive the confirmation mail, but I don't receive the confirmation message on the site.
if I try to change the email address and the username and I click again on "Registrazione" I receive the right confirmation message but in this way i have 2 accounts.
it's not easy to explain but if you try to register yourself to the site (click on "Account personale") you can easily understand the problem.
i really don't know where the mistake is.

thank you