logging directory is set in your hMailserver.ini
Error logging is always on
Typically the logs are at C:\Program Files\hMailserver\Logs\
ALSO, you need to fix the critical warning that you have.
Unless you have a VERY good reason to allow External to external you shouldn't do it.
In the IP ranges page there is a 'default' button. Please click it
Just 'cause I link to a page and say little else doesn't mean I am not being nice.