Taskbar notification doesn't turn off under any condition except clicking on the X

Version: 7.2.34666.0
 After opening the email, the notification for it does not close in the taskbar notification area.


I don’t have 7.2.34666.0 anymore ( have 7.2.34711.0 )
but did you try this :

Menu > Tools >-Settings > General >-Notifications
Tick "Hide popup window and set the time required…