My current team wanted to use Jenkins' "Send separate e-mails to individuals who broke the build" feature. We use Subversion, and our Subversion usernames are not email addresses. And because my team members belong to different companies, we can't specify "Default user e-mail suffix" even if our Subversion usernames were the names of our email accounts.
For a while, I couldn't figure out how configure Jenkins to do what I want. I did a little googling and found out that Jenkins has a "People" page (for example, Apache's* People page is: https://builds.apache.org/people/ ). Clicking on a person's User Id link takes you to their page. With our Jenkins configuration, a user's page has a "Configure" link on the right. Clicking that allows them to enter their name and a variety of other details, including Email address! That should allow me to use "Send separate e-mails to individuals who broke the build" the way my team asked.
* If you want to look at a big, vibrant Jenkins installation, check out the public Apache Jenkins machine: https://builds.apache.org/ Obviously it is read-only, but it has lots of projects, so there is usually something building, and you can see lots of examples of different statuses.