Hello,
As you can see on demo we have 4 fields in contact form:
Name
Email
Phone
Description
ordasvit.com/joomla-vehicle-manager/inde...an/4/2012-bmw-x5-35d
You have customized your form and you 3 fields and if you try send message you get notice
i prega di inserire un nome per la richiesta di acquisto!"
It means you deleted field Name, but doesn't delete verification.
Please, return default settings or delete verification for name.
Thanks
Taras