Hi David, I'm running stable (buster), I just tested purging and reinstalling but didn't solved the problem.
Keep in mind that if you are still using SysV init it would work ok, as the responsible for creating the /var/spool/nullmailer/trigger is /etc/init.d/nullmailer, but if you are using only systemd, I think that init.d file is no longer used, so nobody is recreating the trigger file. In this machine I have purged the sysv packages (initscripts sysv-rc insserv startpar) as recommended by the installation guide [0]. [0]: https://www.debian.org/releases/stable/amd64/release-notes/ch-information.html#obsolete-sysvinit-packages Regards, Alejandro
