Websites can ask to access your webcam (and microphone), but Opera should then ask you ... there's a setting under Settings > Websites related to this - check that. Also see what websites are open.
The setting is: Do not allow sites to access my camera and microphone.
This may be connected to the last update to Opera. I did not have my email up tonight and still got the popup from Zemana. So it's not tied just to email.
As I stated before, Opera will close if I click to block the request, but I've discovered if I create a rule to always block the action, then Opera will not open at all.