If it ever leaked that OpenAI was training on the vast amounts of confidential data being sent to them, they’d be immediately crushed under a mountain of litigation and probably have to shut down. Lots of people at big companies have accounts, and the bigcos are only letting them use them because of that “Don’t train on my data” checkbox. Not all of those accounts are necessarily tied to company emails either, so it’s not like OpenAI can discriminate.