Hi

I'd like to request a feature to send users an email notification when an invoice is fully paid (marked as "Closed").

Here are some specific scenarios:

Scenario 1: Credit Application: When a client has existing credit and the loose credit applied to an invoice, fully paying it, they receive no notification. This leads to confusion and potential overpayments.

Scenario 2: Manual Payment (Record a Payment): When I manually record a payment that fully pays an invoice, the client receives no notification of the invoice being closed.

Currently, Blesta sends an invoice only upon generation, not upon payment. While transaction emails are sent for recorded payments, they don't explicitly confirm the invoice is now closed.

Desired Functionality:

I would like to see an option to send a dedicated notification email when an invoice is fully paid, triggered by:

- Recording a payment that closes the invoice.

- Applying credit that closes the invoice.

This functionality could assist in improving client communication and reducing confusion, especially for clients who rely on manual payments or use account credits.

Thank you for considering this feature request.