Thanks for posting on the Community, @ajharvest
In QuickBooks Self-Employed, the Invoices menu will show all open, draft, and completed (marked as paid) invoices.
While there is no email status, it is only possible for an invoice to show Mark as paid if it has been emailed. For further information on invoicing in QB SE, see here.
Get back to us below if you need any further help! :)