cpgreylistd is unable to start with the following error:
The “NOTIFY_SOCKET” environment variable is empty. at /usr/local/cpanel/Cpanel/Systemd/Notify.pm line 424.
This has been found to be caused by an incorrect
Type value in /etc/systemd/system/cpgreylistd.service.
Modify /etc/systemd/system/cpgreylistd.service by setting the
Type value to 'notify'.
Then run the following commands.