Declare SMTP port and volumes for this image

Refs  #94592

postfix complaines about non-null host address bits in mynetworks

fix docker ip range

postfix config should consider all docker networks local. In fact, if no custom config is supplied the network is correctly set with a larger network mask to account for additional docker networks  but in the setup_conf_and_secret function the network uses /16 mask

Updated glibc vulnerability for Centos
Updated maintainer info
refs #31339

refs #31595: add Chaperone, use Centos 7, remove example folder

refs #28587 Configure for generic usage of postfix, not only as relay; use centos6 to start postfix service