Cron Job for Direct Admin / Linux mail system

Hello, This is going to actually be a pretty simple project. I am lookgng for someone to program a cron job for a linix server ( running direct admin ) that will enable the system to notify the users that their e-mail box is over the limit, or is close to that said limit. It's a pretty simple cron function we are looking for. Ideally we would like it to be a complete script that runs on it's own without the need for installed files on the server, however if needed that is fine. If you require files to be installed on the server for this function, we require those files in a zip or tar format so we can install this onto other servers, and or for backup. We also require documentation on how to configure this. The server you would be working on is a LIVE production server and cannot be rebooted, or cycled without prior notice. Again this should be a pretty basic job, please don't hesitate to drop questions our way if you have them ! thanks, rob