The alert emails that you receive contains information on monitors that go to the down or trouble state. Creating an email template helps you to define the actions that are to be followed after a down or a trouble alert.
Consider the scenario where a monitor goes to the trouble state. In such a case, you would want your team to pause for a few minutes and if the issue persists, restart the service.
Having your own email template becomes useful in such cases. These details can be mentioned in the content section of the template. This way, the corresponding teams in the organization can be effectively communicated with the exact details of the issue and the instructions to deal with it.