It would allow us to @ people directly in Slack threads, since people’s Slack handles are the same as their email.
Thank you! 
Hey @jawon, hopefully you’ve found and been using the BUILDKITE_UNBLOCKER_EMAIL since it was added!
For future travelers to this page looking for that env var, you can find it in our docs here: https://buildkite.com/docs/pipelines/environment-variables#bk-env-vars-buildkite-unblocker-email