One thing you could try that i don't think is mentioned in the link from seavixen32 (forgive me if it is and i missed it)
Display the envelope when you have unread messages?
Click on the little arrow on the notifications bar and select customize
Find this option, click the drop down box and select 'Show icons and notifications'
Click OK and that envolope should only appear while you have unread messages.
Hope this helps.