There really needs to be some love applied to the entire invoice system. Many of my clients report that they go into spam, and even when they don't they don't think it's real. I just had another email from someone who thought it was a scam, using my name.
I love cheqbook, however this entire area is imho a failure. Clients should be able to see all their invoices, they should be able to be customized, they need to be cleaner, and we should have the ability to send a decent looking note.