For every project, the ARN page has a tab called 'Logs'. This page displays entry of all execution logs. Any time a rule is executed, irrespective of its trigger or template - corresponding entry will be created in the logs.
Along with all the related details, these logs also have a link 'View email'. Clicking on this link opens the email that was generated by the rule.
Logs are helpful in keeping track of all instances when the rules were executed.
Cloud version of the app has an additional log status apart from 'Success' & 'Failure' - called 'Suppressed'.
Recently a bug was introduced in Jira that triggers multiple version release events leading to multiple release notes emails from ARN. To keep this in check, whenever a version release event is triggered more than once (for the same version) in a span of 30 minutes, these rule executions are suppressed automatically.