How to include content of the html file to template of the jenkins email-ext?

Easy way to include the html file to email content is to add below line in the default content = ${FILE, path="yourfilename.html"}

this works for me in jenkins email ext plugin

It looks like most easy way is to use 'Pre-send Script' of the Email-ext

Script looks like this:

def reportPath = build.getWorkspace().child("HealthTestResults.html")
msg.setContent(reportPath.readToString(), "text/html");

It renders content of the HealthTestResults.html located in the root of the workspace just as body of the message.