I would like to ask how do you are you implementing $SUBJECT in your project?

I tried to setup email-ext plugin, but there was CVE [1], which disabled option to send emails to a user which are not registered in Jenkins.

There is a workaround to shift this behavior, but I am not sure whether you want to enable it:

So my question is, what would be the best solution to implement notifications in current ci.centos.org Jenkins instance? 

Thanks,

Pavel Kajaba

[1] https://jenkins.io/security/advisory/2017-03-20/#emails-were-sent-to-addresses-not-associated-with-actual-users-of-jenkins-by-mailer-plugin-and-email-extension-plugin