Recently I’ve noticed that greylisting didn’t work any longer on my server. The reason for this was, that the service “postgrey” did not start any longer.
A manual start using the command line was still possible but not starting it as daemon.
A quick fix for this is to modify the file
/etc/sbin/postgrey as following: change the shebang in the first line.
#!/usr/bin/perl -T -w
However this also makes the script less safe as well. The better solution is a modification of the script as described on https://github.com/yasuhirokimura/postgrey/commit/9673b54064691a5b9c295ffea340d8a1f9ee1cb8.