Or... you can do it all with Add Ons.
Juiced Technologies offers the ExactFormsPlus! tool which you can create Invoices with and store them either in QuickBase or in Amazon S3 and they also have the QBCourier tool which is great for sending out professional emails (fully customized) with attachments from files stored in QuickBase or from Amazon S3.
If you go the route of creating Invoices within QuickBase from data stored there, they also have a Batch Processing tool to generate them all at once.
Highly recommend talking to them about your situation to see what's right for you.
Neil's option is valid - but you can't send a physical file attachment from QuickBase and the email notification is limited in its formatting, depending on what you want your email to do.
