I've notice that alot of people have this problem. Everything works, and you create invoice. But when you click "Email to Client", it says "There was a problem sending the invoice." And nothing more!
If I try send it agin it says "Successfully sent 0 Web Invoices(s)."
This plugin worked for me for several hour yesterday, but then i stopt working, after hours and hours of searching this error I cant get it to work again!
I cant remember changing anything special when it broke down. I have deletet the files, deleted the database, AND deleted ALL the options remaning and reinstalled. Nothing.
Installed the plugin in another site, works perfekt again! (?)