Annadf63 on "[Plugin: Contact Form 7] Parameter -f mail@mydomain.it"

Hi..sorry for my english.
I have a big problem. I don't receive email sent by contact form..
I have asked support at my hosting (Tophost) and it have reply that I must insert this command: "-f mail@miodominio.it" into plugin's php. Because they block the email sent by contact form..!! How and where i can insert this command?? thank you..

http://wordpress.org/plugins/contact-form-7/