Multi notifications from Email fields on the form

Hello,

I am trying to send a notification from an input field (email in a first gravity form) to this email.
Example :
Step 1 : user1 (user1@mail.com) fill a first input field (user2 mail : user2@mail.com) and submit this gravity form.
Step 2 : notification send to "user2@mail.com"

Do you guys, have any ideas to resolved my problem ?

Thx a lot,
Regards