You may want to define multiple email recipients for the notifications generated by the Cache to monitor critical events. To achieve this, you need to add the email addresses to the cluster_conf.xml file. Follow the process described in this article on Updating the Cluster Configuration and add the email addresses within the alert-email tags by separating them with spaces.
Please see an example below:
<alert-email>email1@example.com email2@example.com</alert-email>