I think it is safe to say the emails have nothing to do with stealing code. He copied his email history so he could personally have it. Lots of people do this

I think it is safe to say the emails have nothing to do with stealing code. He copied his email history so he could personally have it. Lots of people do this when leaving a job, even when they are not supposed to. It is your correspondence for the last X number of years, you want a personal copy. Carmack would have a greater incentive to copy the emails since he clearly was blurring the lines between personal work and private work while working for id which was inherited by zenimax when they bought id.