Jenkins email plugin doesn't send email to user who broke the build

For version V2.61 or above this can be configured via a radio button.

Go to

Manage Jenkins -> Configure System -> Extended E-mail Notification

and tick the radio button for Allow sending to unregistered users

Edit: If this does not work, see https://stackoverflow.com/a/45353810/492336 for another solution.

OK, after some experiments this is what I found out:

Jenkins takes the email part of the committer (not the author). For example for a commit message that looks like that:

Author: John Smith <author1@example1.com>  2017-07-27 17:15:39Committer: John Doe <committer1@example2.com>  2017-07-27 17:15:39Parent: 9c3ff18dda8ca6f7b7ac4ebab4c76d3c85891a33 (commit)Branch: master

Jenkins will take "committer1", and create a brand new user under People with User ID "committer1" and email "". Unless that user has a password however, it will be considered unregistered so you need to go to Configure for that user and add a password field to it:

So this is one way to fix the error, but you have to do it for every user and in a big team it can be tedious.

Put the line bellow in your jenkins startup script

-Dhudson.tasks.MailSender.SEND_TO_UNKNOWN_USERS=true

The newest Jenkins security directive only allow sending mail to registered user. The line above bypass this configuration.