Hello 
You may want to consider disabling the "ConfigServer Mail Queue" plugin and using the cPanel mail queue option instead:
"WHM >> Email >> Mail Queue Manager"
We've made significant improvements to the functionality of this option in version 11.32. As for the lost emails, you can check the following log file to determine if they were delivered:
Code:
# /var/log/exim_mainlog
You may need to search for specific entries, so using "exigrep" may be useful. EX:
Code:
# /usr/sbin/exigrep email@domain.com /var/log/exim_mainlog
Simply replace the "email@domain" entry with an actual email account or message subject.
Thank you.