In plugin version `2.100` and older, users could configure jobs on a controller to modify the 'from' attribute at a job level (using Pipeline `from:` , or freestyle `Project From`).

Some companies have internal policies which do not allow this, and it can be unexpected when an email 'from' can be controlled by any user who has the `Job/Configure` permission or the ability to commit to a repo which contains a Jenkinsfile.

With this feature, the 'from' field of emails should always uses the `from` address defined at `Manage Jenkins` -> `System` -> `System Admin e-mail address`, and would not be configurable at a job-level.

Users that would like to go back to the previous behaviour can add the system property as a startup argument: `-Dhudson.plugins.emailext.enable-job-from=true`.

A message is emitted to the controller logs when the 'from'/'project from' field is used by a job, at a `WARNING` level if the 'from' address was ignored, and 'INFO' level if the system property is set (to remind about the deprecation).

This idea is a re-design of this feature after discussion in https://github.com/jenkinsci/email-ext-plugin/pull/479