I started watching https://ci.chromium.org/buildbot/chromium.infra.cron/Build%20From%20Tarball/ in https://chromium-review.googlesource.com/1141576. It used to work in the past, but looking at the bot it appears none of the recent build failure emails (for e.g. https://ci.chromium.org/buildbot/chromium.infra.cron/Build%20From%20Tarball/490) have been delivered.