Are you aware of the MNLINK best practices about the subject of overdue notices and billing? These practices have been reviewed and approved by the MNLINK operations committee. Some of these practices only apply to the participating MNLINK public libraries. They also apply to the MNLINK requests that were filled through Minitex Resource Sharing from a MNLINK public library when the VDX automation missed a location on the first rota pass.
I am often asked to weigh in on the topic of billing, and this page is where I turn. You too may use these clearly written guidelines to keep yourself informed.
Here are some additional suggestions that would relate to your local situation. Do you have bills set up to automatically go out via email from your circulation? You probably wouldn't see those sent emails. If you can have multiple email addresses on a circulation account you could have your location copied.
Do you have a dedicated email address for billing notices? That might be a good way to track notifications. You may have other ideas to help track your billing notices.