Ok … your first problem is that you are on a blacklist – that offers no path for removal.
More information about UCEPROTECTL3 can be found at their website: http://www.uceprotect.net/
Reason for listing - Your ISP AMAZON-02, US/AS16509 is UCEPROTECT-Level3 listed for hosting a total of 24314 abusers. See: http://www.uceprotect.net/rblcheck.php?ipr=220.127.116.11
So, first and foremost, you can switch to another VPS provider which actually cares about their IP reputation and blocks spammers from their network.
Another option is to use a SMTP relay service. I have developed one for MiaB users in response to this issue. Using a PAID SMTP relay is a must as spammers have also ruined the reputation of the free levels of various SMTP relay services. If you want any information about it, please ask.
So, my initial conclusion without doing heavy research is that your IP reputation is what is causing your issue. You are using MiaB itself for DNS, so I would not think that there are any DNS issues.