Check email delivery.
It is possible to send the trigger message in three ways.
See: cse-add-client.sh
can-send-email.sh --add HOSTNAME http://HOSTNAME/SECRET-DIR/cse.php
can-send-email.sh --add BOUNCE-HOSTNAME mailto:DOESNT-EXIST@DOMAIN
can-send-email.sh --add FORWARDED@ADDRESS mailto:FORWARDED@ADDRESS
It is very important to whitelist all sender IP-s on CSE server.