How email handler work from Sciptrunner

[Shah Baloch]

I noticed there is an email handler option in script runner, but don't have any clue how it works, there isn't any clear documentation. Currently, we are using Jira email handler, whenever to receive an email it creates a ticket. We are using the email handler for Nagios alert, so Jira email creates a ticket with each alert. We would like to create a new ticket only if there will be a problem, but once you get a resolve email it should close the ticket and not create a new ticket or if the issue continues it should post an email in the comment of an existing ticket. 
I thought script runner might solve the problem but I didn't find the proper user guide, I might don't use the right keyword to search it. Can someone walk me through all process that how to use scriptrunner's email handler option? I really appreciate it.