Which of the following is NOT a requirement for an unauthorized insurer's eligibility?

An unauthorized insurer does not need to maintain a reliable customer service department to be eligible for doing business in Michigan. The primary requirements for such insurers focus on proving their financial stability and regulatory compliance, which are critical to ensure that they can meet their obligations to policyholders.

The requirement to file the Uniform Certificate of Authority Application highlights the need for formal recognition and adherence to regulatory standards, while demonstrating financial stability ensures that the insurer has the necessary resources to cover claims. Additionally, maintaining a minimum level of capital and surplus, in this case at least $1,500,000, serves to protect consumers by ensuring that the insurer can fulfill its financial obligations. However, a customer service department, although important in practice, is not a regulatory requirement for eligibility as an unauthorized insurer.