$!issue.project.key
or $!issue.getCustomFieldValue("customfield_12345")
.$parser.parseDate("dd/MM/yyyy", $group1)
.$group1, $group2, $group3
$parser.cascade("<parent-value>", <child-value>")
.$parser.cascade($group1, $group2)
or$parser.cascade
("static value for parent", "static value for child
")"<field from the field rule>=<value from the field rule> AND project=<project from the mail handler context> AND issuetype=<type from the mail handler context>"
priority=Blocker AND project=Support AND issuetype=Request
"Order Nr"~"A001" AND project=Customer Orders AND issuetype=Customer Request
"Order Nr"~"A001" AND project=Customer Orders
"Order Nr"~"A001" AND issuetype=Customer Request
"Order Nr"~"A001"