Great tool! I'm able send mass emails with no problems at all; it's extremely easy use even if have never done this before or used any other similar tools in my life (I've been using ZBP since 2012).
There is nothing bad about zero bounce solution - great customer support team who answers questions fast & efficiently every time we need help solving some problem related to our campaigns management process flow ;-) It helps us manage several thousand of contacts per day without losing customers due poor delivery service quality which would be otherwise inevitable when dealing withe large number of recipients. We're very happy here :-D So far everything was perfect but recently i had one issue where zbp just stopped working from 1st Jan 2016 till today 2nd April 2017 after restarting computer multiple times there were still issues like "connection closed" etc., so maybe something has changed over those days? Not sure exactly what happened during last.