I have a server CentOS 5.3 and WHM/cPanel 11.24 installed. In exim log files I noticed these wordings next to most of the emails.
Warning: Sender rate (a number, like 2.4) / 1h
Do you have any idea what it means?
cPanel has a ratelimit option on the exim
configuration.
Basically it tells you for each IP address its send rate.
You can configure a maximum send rate per IP per hour (after which that IP is temporarily rejected, i.e. with code 4XX) to reduce the server load.