In order to set email alerts in Cacti you need to install the Cacti Plugin Architecture. This can be found at http://docs.cacti.net/manual:087:1_installation.9_pia#installing_plugins , this is a good document for instructions on how to install and add plugins. Once this is installed be sure to go under the Utilities section of Cacti and select User Management. Once in User Management you will need to select the users you would like to have the ability to set Thresholds. You would do this by selecting the user, go to the realm permissions tab, then put a check on the Thresholds you would like to allow the user to have access to. Next hit save and you are done.
Also I found a little gotcha on the installation that had me stuck for a few hours. When you are on the final stages of the installation of the plugin architecture make sure you have the settings plugin installed. This plugin should be set in the config.php as ($plugins = ‘settings’; ) . Also you do not need to add other plugins to the config.php , just load them in the /cacti/plugins directory . Then once they are there go to the configuration section , plugin management and the plugin will appear.
Hope this helps!
From the Sozo Hosting Support Staff