I have Youtube installed and its updated to the latest version.
Is Youtube also causing this?
Started to work at 8 CET today with 100% around 10 CET (2 hours later) the battery was on 20 %.
I could see under battery in settings that the default mail app was draining battery at 67%, the things is that I have the settings to fetch mail when opening the app so its not running in the background, I have also closed this under Settings --> General --> Background App Refresh, but its still draining as ****.
I ended up deleting the app few minutes after 10 CET and now at around 16 CET the battery procent is around 12% I have been using the phone during that time also.
Basically I ended up uninstalling the default mail app and I am using Gmail app now, its seems to have resolved my issue now but surly this should be brought up for a permanent fix in the future.