Hey, we only just saw this now: Emails run through a filter before being pushed to your mailbox and encrypted there. So we can see spam emails, but with Tuta Mail you can also send end-to-end encrypted emails of which we see nothing. Plus, if you report emails as spam (e.g. by dragging them to the Spam folder) you are being asked whether you want to give us a copy of the content so that we can improve the spam filter.