The pain is all up front. You configure PowerMTA to slow down its sending due to the responses of the various email providers so they never block you. As the tr

The pain is all up front. You configure PowerMTA to slow down its sending due to the responses of the various email providers so they never block you. As the trust for your ip goes up you can send at a faster and faster rate. Also you then store all the email bounces and run a cron job to clean your list. Usually I stop sending to emails that return hard bounces and ones that have soft bounced three times.