BQool does let you create professional invoices that you can send to your clients by email and then download it with PDF format as illustrated in an example attached below.
Remember when you send out emails containing VAT invoices. The Invoice needs to be PDF form as Amazon suggested in their policy.
As an Amazon Seller, it's required to comply with all applicable legal requirements as well as the Amazon Service Europe Business Solutions Agreement and relevant Amazon policies. Amazon Business customers require invoices and receipts for tax and accounting purposes. Failure to comply can result in actions taken against the selling account.
For more relevant information, please click on the Youtube video below.