If you are using the cloud for email they can usually see all of your activity. Email is also how you typically reset passwords. It can expose corporate secrets

If you are using the cloud for email they can usually see all of your activity. Email is also how you typically reset passwords. It can expose corporate secrets. In practice, nobody encrypts their email. And even if they do, the cloud still gets all the metadata. Running your own trades the above issues for other issues, but depending on your priorities and fears it might be worth doing.