I use Jenkins Version 1.642.1. After an update by the Email Extension Plugin to Version 2.41, the plugin send me an mail with the following text:
"Jelly file [html-with-health-and-console] was not found in $JENKINS_HOME/email-templates"
In Version 2.40.5 is it successful and I don't change something. You can see the settings in the picture. The file exists (/var/lib/jenkins/email-templates/).