Problem Definition

JIRA Service Desk not sending any email notification when issue is Closed

As stated in this documentation: https://confluence.atlassian.com/servicedeskcloud/managing-service-desk-notifications-732528936.html
When a customer submits a request, they receive email notifications as the issue reporter when:
the request is created
a comment is added to the request
another participant is added to the request
the request is resolved with a set resolution field
the request is reopened with a cleared resolution field

So by default there will be no notification sent when the request is closed.

Suggested Solution

JIRA SD will send email notification to reporter when issue is Closed