Preliminary Concepts
The 'Customized email Template' is a configurable option of the Herzum Approval add-on.
It's possible to configure it in the Global Configuration administration screen.
Solution
The customer requirement has been satisfied through the configuration of Email Template.
At first it's necessary to configured the Conditional Rule from Approval Administration Panel, choosing "Add Conditional Rule"
It will open a configuration panel, which contains a possibility to configure the rule, based on JQL . In order to satisfy the customer requirement the rule is "priority=high and issuetype = Emergency"
It's possible to choose the evaluator of the conditional rule and additionally to verify the validity of query using on hand lens icon.
Last in the Email Template choosing the tab "Approval Request" click on "Add E-mail template for project".
Choosing "Configure" it will open the E-mail Template Configuration, which to allow to specify the Condition to prioritize the emails, as showed following.
In addition it's possible to customize Header, Subject, Body, Approve/Reject Instructions, Footer, Logo and which one of the Field of issue insert to email.
