Refer information to a friend/associate

This hook isn't in the documentation on that page. It's in the new developers documentation that will be launching at the end of this month with the final release of 1.5.

The hook you use to set the Send To address of the User Notification is the gform_autoresponder_email hook.

Here is an example of this hook being used.

<?php
add_filter("gform_autoresponder_email", "change_notification_email", 10, 2);
function change_notification_email($email, $form){
//creating email list from fields 2 and 3.
return $_POST["input_2"] . "," . $_POST["input_3"];
}
?>`

The example above returns the values of 2 fields from a form as the Send To address.

If you want to apply this only to a specific form you would change this:

add_filter("gform_autoresponder_email", "change_notification_email", 10, 2);

To this:

add_filter("gform_autoresponder_email_1", "change_notification_email", 10, 2);

The 1 in the above add_filter call that was added to gform_autoresponder_email is the form id. This way you can specify a specific form.