e-mails were released as part of an antipoaching lawsuit (wage supression/wage theft); Apple, Google and others settled.
https://www.cnet.com/tech/tech-industry/apple-google-others-...
https://www.reuters.com/article/us-apple-google-lawsuit-idUS...
Even by then most of those same companies had already settle another case that included ending those agreements:
https://www.cnet.com/culture/doj-settles-no-recruit-claims-a...
https://www.justice.gov/opa/pr/justice-department-requires-s...