I was just wondering if there is any possibility to clean our email list using PMTA. I know we can achieve this with the bounce processor but in that process, it will first try to deliver the email when it hit the ISP and if the bounce rate is too high you domains and IPs are at risk. Does anybody know a process when it will only make an SMTP connection, and try to find out if the email exists or not (Without getting it delivered)? I believe that's what an email cleaning service provider does.