Basic Workflow

Create an SNS topic to receive alarm messages.
Create an email platform if you use an email endpoint. Skip this step if you use the HTTP webhook, DingTalk, or SMS endpoint.
Create an endpoint (email, HTTP webhook, DingTalk, or SMS) and subscribe the endpoint to the SNS topic you created in Step 1.
Note: Related SNS resources mentioned above can be reused by multiple alarms.
Create an alarm and set Action to the SNS topic you created in Step 1.