Problem: You send a notification to your customer email and customer answers it. When that email is processed by Jira or ServiceDesk incoming mail processor, then the whole email (answer and original body) is added as a new comment to the ticket. You only want the latest customer answer to be added as a new comment.
Solution: Both, Jira and ServiceDesk make specific assumptions on how to separate the response from the original message being quoted. The response should be separated from the quoted message like this:
The dashed line on the second page acts as a separator between the quoted message and the new comment added by customer. The text on line 5 can be customised as you wish.
You need to add the code above at the very beginning (top) of your notification template.