https://www.salehram.com/2017/03/14/a-story-of-a-project-3600-users-to-g-suite-in-60-days-day-4-starting-up-migration-the-ndrs-mishap/
A story of a project: 3600 users to G Suite in 60 days! - Day 4: Starting up migration, the NDRs mishap!