If you create a Retainer without activating it, means you just save it as a draft, you have got yourself a ‘Pro-forma Retainer’.

This invoice is only visible from account owners and administrator’s profiles. It isn’t displayed on ‘Retainers invoices list’ from the Client’s profile.
In order to inform a client about this invoice, the zistemo account owner (or administrator) can send the Pro-Forma Retainer to your client by email by simply clicking on ‘Send to client’:

If the client accepts the Retainer, the zistemo account owner (or administrator) can instantly activate this Retainer by clicking on the ‘Activate and send’ button:

… and now the Activated Retainer will be visible from the Client’s profile.