PopTray and Windows Task Manager

[groucho7]

On my Windows 8.1 system, Mozilla Thunderbird is the default e-mail client in PopTray. The Windows Task Manager Startup tab shows PopTray E-Mail Notifier(2), meaning it includes two processes that start up with Windows. If you expand it, you see both PopTray and Thunderbird. However, while PopTray shows up in the Task Manager Processes tab, Thunderbird does not. Is this a problem with Task Manager or with PopTray? Does PopTray automatically start Thunderbird? If so, is there any way of preventing it from doing so? Any insight into this issue will be appreciated.