Right now, logs are available only on the cloud version. We will update this documentation when they are also available for the server version.
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.