On 05/20/2015 10:34 AM, Mike McKoy wrote: > There must be something else keeping the instance of postfix from listening on that IP & port.... I'm thinking something at the CENTOS level. I cannot get the port to open on 172.30.1.65 regardless of what I try. > > Again here is the config I have in /etc/postfix-immt/main.cf. Are you sure those files are being used, rather than files in /etc/postfix? If changes that you make there aren't affecting the behavior of postfix, the simplest explanation is that they aren't the correct files.