We need a script that is already written to send out monthly invoices to customers that we manually enter into system. The invoices will go out automatically on a specified date depending on what service they subscribe to. Customers will be paying via check, so not integration with gateway is needed, etc. Just the script and database on server only. In future, we may want to expand.
NOTE: In your response explain what script you will install to achieve this. Do not want from scratch.