As i said...you may have to check your settings....you made me work
just limited one of my test accounts to only 5 emails per hour, then simply created a php file with a mail() function to send an email to one of my email accounts, reloaded that file 6-7 times after 5th i see the error message "Domain mydomain.info has exceeded the max emails per hour (5) allowed. Message discarded." in the exim logs.
Good luck!
Good luck!