Hello,
I'm using nbill more then a year, everithing was fine, but yesterday i recieved 3 nbill error e-mails saying "A callback was received, but nBill could not verify that it came from Paypal"
There were no changes in apache, php, firewall and nbill configuration during last few months.
Now i have to mark invoices as paid manually.
Please help.
Regards,
Alex.