netDumbster.smtp.Configuration.GetRandomUnusedPort C# (CSharp) Method

        private static int GetRandomUnusedPort()
        {
            try
            {
                var listener = new TcpListener(IPAddress.Any, 0);
                listener.Start();
                var port = ((IPEndPoint)listener.LocalEndpoint).Port;
                listener.Stop();
                return port;
            }
            catch
            {
                throw;
            }
        }

 /// <summary>
 /// Configures a random port.
 /// </summary>
 /// <returns></returns>
 public Configuration WithRandomPort()
 {
     this.Port = Configuration.GetRandomUnusedPort();
     return(this);
 }