Just use mail_2 instead of mail
$mail = $contact_form->prop( 'mail_2' );
$mail['body']= "CUSTOM BODY TEXT";
$contact_form->set_properties( array( 'mail_2' => $mail ) );
Just use mail_2 instead of mail
$mail = $contact_form->prop( 'mail_2' );
$mail['body']= "CUSTOM BODY TEXT";
$contact_form->set_properties( array( 'mail_2' => $mail ) );