Did they hire their own consultants to do it?
Christ, pay me $10M and I'll bring an army of 30 geeks to turnaround this landfill fire. I did a startup that M&A'ed organization email providers of all sorts (Exchange, postfix, sendmail, etc.) to aggregate them for efficiencies at scale.
1. Tested and complete backups
2. Sample testing
3. mbox migrations
4. Exceptions handling
5. Further testing
6. Cutover
IBM hires... bodies.
And I'd imagine internal IBM IT is... anyone they can't use to bill a customer with.
Ouch.
IBM should use this crisis as an opportunity to fire horrible IT resources, e.g., managers and staff.