I have been using Email Extension Plugin for a long time in order to report our Junit Test Reports with Groovy HTML scripts. But after upgrading to Jenkins 2.274, I couldn't able to use Email Extension Plugin. I recieve mails like below. 

subject : [$BUILD_STATUS] - $PROJECT_NAME - Build # $BUILD_NUMBER ($BUILD_ID)

body : ${SCRIPT, template="groovy_test.groovy"}

It was working fine until Jenkins 2.273, as you can see below.

I tried to upgrade latest Jenkins version(2.282) but the result is the same. When I rollback my Jenkins version to 2.273, I have no problem. Why I cannot recieve groovy HTML emails? If you need anything else, please contact with me.