Daniel, et al.
I was preparing a fix for this by copying some support scripts from other exporters when I noticed a couple of things, and wanted to check with you before making any change. This exporter is running with user postfix, while all the others use the prometheus user. I understand that you need to access the queue directly, but this could be done by granting the postqueue group when starting the process instead. Another thing is that this requires a special log configuration (duplicating all postfix entries to a new file, and making that file writable by the user this exporter runs as), which probably should be documented in a Debian readme, and I have no idea how to do this with systemd? Also, I'd suggest moving that log to /var/{lib,log}/prometheus Honestly, back in the day I had looked at this exporter and decided it was not great because of the log requirement, and started using mtail for monitoring postfix.