UX: Use unique subject lines for invoices

[anthonysexton]

When receiving an invoice from CaptainCore billing, the subject line should have a unique identifier e.g. client code & invoice number in it so that recipients can easily PDF it for accounting purposes, without having to set a consistent name to avoid filename conflicts.

[austinginder]

Anthony, Thanks for the feedback. Currently the billing notifications are being inherited from WooCommerce itself. I think it make sense to roll my own notification system or at least exceed the current built in WooCommerce emails. I'll see what I can come up with.

Regarding PDF, the billing system does now include a downloadable PDF option. From your invoice you can now select then download PDF icon in the top right.