/**
 * Optional settings for the lookup request.
 */
interface LookupOptions {
    /**
     * Custom headers to include in the request.
     * Note: `User-Agent` will always be overridden by the library.
     */
    headers?: Record<string, string>;
}
/**
 * Response returned from the throwaway.cloud API.
 */
interface LookupResult {
    /** Indicates the request succeeded. */
    success: boolean;
    /** Whether the subject is considered disposable. */
    isDisposable?: boolean;
    /** Any additional fields returned by the API. */
    [key: string]: any;
}
/**
 * Looks up an email address or domain against the throwaway.cloud API.
 *
 * @param subject - The email address or domain to look up.
 * @param options - Optional request headers (excluding `User-Agent`).
 * @returns A promise resolving to the API response.
 * @throws If the subject is empty or the API returns a non-2xx response.
 */
declare function lookup(subject: string, options?: LookupOptions): Promise<LookupResult>;

export { type LookupOptions, type LookupResult, lookup };