Invoices Not Sent
            When an Invoice is first created as a draft, it has the status Open. It is also automatically flagged as not 'Sent to Client' and appears in the 
Not Sent list.
            
            When it is ready to be sent, you can 
email the PDF version to your Client. This automatically marks the Invoice as having been 'Sent to Client', and 
            the Invoice moves out of the Not Sent list.
            
            If you do not send invoices by email, but have 
downloaded and printed the PDF version to send by post mail, 
            you will need to edit the Invoice and check the 
'Sent to Client' box in the Client section. This will move the Invoice out of the Not Sent list.