-
I store my data on iCloud. Also I use Google Drive. But still I worry that something can go wrong and I miss important data, so I create the backup copies on my notebook. Usually I save my emails as pdf files (here https://emailindetail.com/ helps me a lot). It is convenient, because I can work even when I don't have access to the Internet, especially when I'm on the road.
-
I agree with the previous commentator that it is best to duplicate the two methods: cloud storage and local storage. This provides a good guarantee of information security.