Does Opera Mail -the stand alone version- only notify of new mail when it is minimized on the Taskbar?
That should not be the case. It should notify you whenever. However, notifications are quirky for some people. No explanation as to why.
You can always close down Opera Mail and edit operaprefs.ini in the preferences folder. Just delete the Show notifications for new messages line under the User Prefs section. That will cause Opera to use the default (of 1), which is to show notifications.
To keep it all in perspective, though, the user has to first intentionally enable the microphone at a misbehaving site which, itself, is the only site that can listen in thereafter, regardless of what site a user browses to in the session - provided the misbehaving site first creates a "keep alive" pop-under window behind the Chrome window (so as to hide its presence from the user). If the browser or the pop-under is closed, the exploit ceases. It's still a potentially harmful exploit, but certainly not as bad as if a site could auto-activate a user's mic or if any other site could listen in to a mic after it was somehow activated at a different site.