On a clean machine which had not been running postfix previously - i installed and started postfix with default configs without error. This suggested something changed in the configs which I missed somehow. Looking in configs it is clear that the variable daemon_directory has changed and needs to be updated on existing installs or postfix won't run (see below). Existing installs need to ensure to change it in main.cf to be: daemon_directory = /usr/lib/postfix/bin Default previously was without the '/bin' on the end. I do note that there are shared library files in /usr/lib/postfix but all executabled have been moved to the '/bin' subdir. Gene ========================= Supporting Information ================== ---------------- Machine with mail server installed ----------- # cd /etc/postfix # egrep 'postfix-script' * */* postfix-files:$daemon_directory/postfix-script:f:root:-:755 postfix-files:$config_directory/postfix-script:f:root:-:755:o postfix-files:$config_directory/postfix-script-sgid:f:root:-:755:o postfix-files:$config_directory/postfix-script-nosgid:f:root:-:755:o # postconf | egrep daemon_directory daemon_directory = /usr/lib/postfix ------------------ Fresh Install machine postconf | egrep daemon_direct daemon_directory = /usr/lib/postfix/bin ========================= End Supporting Information ==================