Prestashop Module Send to a Friend allows Spammers to abuse the feature for sending emails to a friend

How I have discovered the security flaws in Prestashop Module - Send to a Friend One customer reported that the in-box for isPrestashop store email was containing hundreds of bounced emails, with spam, so I requested him to forward one of that emails to me. Just by open it, was obvious that the email was originated from is store, by the native Send to a Friend module. This module is installed, by default, on the original Prestashop theme and in many other third part themes.