When I send a payment notification, the email "From" field uses the name of my blog and the email address on the WordPress General Settings page.
It should instead use the business name and email address in the WP-Invoice settings page.
Also, an option to include the business' email in the bcc or cc of the emails sent would be great because there is no record of emails sent from WordPress (can't just look in my Sent box --although that would be a great way to handle it too). The need is for a sequential list of emails sent. I was able to manually put two addresses on the "To" line, but an option would be much nicer (and look better for the client).