Sadly it's my fault. I hit TEST on the Advanced>Notification screen but I never hit save... definitely works now when mail.php is called from the shell.
I did start using Node RED as my email middleman with curl being called from pfSense... that also worked well. However, generic mail.php is obviously much simpler.
This is the piece I'm trying to automate notifications for: https://forum.netgate.com/topic/118401/openvpn-server-notification-on-connect
Thanks for the input, thread can be closed...