[Feature request] Ability to chose which build events trigger an email notification

When subscribed to email notifications I receive an email for all build events (STARTED, FAILED, SUCCEED, etc).

I would like to select which build events should trigger an email notification.

The issue names no files, tests, or entry points. Start by locating the existing build-event email notification flow and the subscription settings, then define how users select events such as STARTED, FAILED, and SUCCEED; done means only the selected events trigger emails.

Written by the indexing model from the issue text.