I felt extremely uncomfortable clicking on a button to go to a QuickBooks site to put in banking info.

People should not be clicking on links in emails. And responsible businesses should not be encouraging it.

People should REALLY not be clicking on links/buttons in emails and putting in payment information.

People should have ALARM BELLS GOING OFF if they see a link in their invoice email to a generic, multi-tenant site where anyone can pretend to be someone else.

Clicking on a button/link in an email is a good way to have your identity, or worse, your money stolen! lol

Please, give users the instructions on how to manually type in an address, or even copy/paste a URL into a browser - either is infinitely better than clicking a button/link in an email.

Better yet... maybe think about using something like... oh, I don't know... Paypal?