Display HTML page inside mail body with Email-ext plugin in Jenkins

It should be something like this:

Navigation:

Configure -> Editable Email Notification

Default Content:

${FILE,path="path/result.html"}

Besides reading the file with body: ${FILE,path="index.html"}, you need to set the proper content type, either globally or explicitly for one execution, with mimeType: 'text/html.

emailext subject: '$DEFAULT_SUBJECT',
                    body: '${FILE,path="index.html"}',
                    recipientProviders: [
                        [$class: 'CulpritsRecipientProvider'],
                        [$class: 'DevelopersRecipientProvider'],
                        [$class: 'RequesterRecipientProvider']
                    ], 
                    replyTo: '$DEFAULT_REPLYTO',
                    to: '$DEFAULT_RECIPIENTS',
                    mimeType: 'text/html'

It worked for me with Jenkins 1.558

${FILE,path="target/failsafe-reports/emailable-report.html"}

Look deeper into the plugin documentations. No need for groovy here.

Just make sure Content Type is set to HTML and add the following to the body:

${FILE,path="my.html"}

This will place the my.html content in your email body (location of file is relative to job's workspace. I use it and it works well.

I hope this helps.

EDIT: Note that you must have the Jenkins version 1.532.1 (or higher) to support this feature with the email-ext plugin.