The invoice is issued for 10 days before the payment date for the customer to have time to pay it on schedule. The first notification is sent by our system automatically to inform the customer about it. If the invoice is not paid - the second automatic notification is sent on the date of payment to warn the customer that 3 days are left to pay out the invoice. And then billing dept sends the final notification - the ticket to the main customer's mail and warns about suspension of the account if the invoice is not paid in time. Sometimes our customers contact us and ask for some time to pay the invoice as there can be some problems with the payment or they are not able to pay the invoice in time. We are always ready to wait for the payment without suspension of the account. We do it because we value and trust our customers.