In this module, only logged in customer can send invitation to his friends. The customer sends invitation using email with a unique coupon code. When the invited user get create his account, at that time he has to enter that unique coupon code. Once the invited customer gets registered, s/he automatically gets the discount of 15 Euro for his first order. When the invited user place his first order, then a new email will be sent to inviter customer and s/he gets the 10 percent discount.