As added information, I did not install postfix directly; it was installed as a dependency to the Linux Standards Base package lsb: lsb depends on lsb-core, lsb-core depends on postfix.
As added information, I did not install postfix directly; it was installed as a dependency to the Linux Standards Base package lsb: lsb depends on lsb-core, lsb-core depends on postfix.