By default, Jira and Service Management type system templates include in a notification all the fields that have changed during an issue update. The fields to be included can be changed without creating new custom templates. It can be done by updating the global custom macros. For issue create notification check out this how-to.
Step-by-step guide
Change global custom macros
Go to Notification -> Custom Macros -> Edit.
Add the following script updating the list as necessary.
## Specify the fields to be shown during a JIRA issue update notification #set ($serviceJiraUpdateFields = ['issuetype','assignee','created','updated','priority','reporter', 'security','customfield_10200', 'security','labels'])
## Specify the fields to be shown during a Service Desk issue update notification #set ($serviceDeskUpdateFields = ['issuetype','summary','description','customfield_10200', 'security', 'labels'])
The screen should look like this:
Once saved, it can be testing by using the Preview tool:
Go to Notification > Preview
Select either Issue Update JIRA or Issue Update Service Desk template
Select a preview context
Hit Preview
The email now only includes the fields in the $serviceJiraUpdateFields list that have been changed during the operation.
If other fields that the specified ones have been changed, the email will be empty (no useful information rendered) and the notification will be ignored.
This change is global and it will reflected in all system templates. It is the simplest way to define which fields to show. If you need more customization, please visit How-to Create custom Theme and Template Sets.