Apparently there is a new system ID in CentOS 7 that I did not know about.
One of the clean up processes I did when setting up that AMI was to delete /etc/machine-id
I thought it would recreate itself, apparently you have to run systemd-machine-id-setup to make a new one.
I found this out while trying to troubleshoot mail routing in my setup.
When I was on the mail proxy /var/log/maillog was empty. Recreating the machine-id file and rebooting it helped.
Another side thing I found was /var was filling up on my main mail server. Apparently I filled up the inodes on this in /var/spool/clientmqueue.
All is better now.
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