Variable BillingEmailsForm`Const`

BillingEmailsForm: React.FC<
    {
        action: RecurringFeeFormAction;
        customerId: string;
        emailAddresses: readonly string[];
        savedNote?: string;
        startOpen?: boolean;
    },
> = ...

The extra addresses mailed each invoice and receipt, behind a disclosure that starts open while an invoice waits for an address.