Currently Outlook works like this:
How to make it as simple condition:
? So until I Outlook mark new messages as read, notification should stay.
You can't. The function just isn't there in Outlook.
The only thing you can do is to increase the timeout (somewhere in the settings panels of Outlook, but I don't have Outlook here to check where exactly).
There are 3rd party mail-notification tools that can work with Outlook. (Both as a Outlook add-in or as a separate program that monitors your mailbox independently from Outlook.)
A former co-worker of mine used to use one of those for this particular feature (so there is at least one add-on that can do it), but the name of that program escapes me.
For the fellow search engine travelers, there is a work around.
You can set the Alert timeout to 50 days, using a registry setting:
Key: HKEY_CURRENT_USER\Software\Microsoft\Office\<version>\Common\DesktopAlerts
Value name: TimeOn
Value type: REG_DWORD
Value: 4294964295 (Decimal)
If this key isn’t available choose Edit-> New-> DWORD Value and name it TimeOn (case sensitive!).
On Windows 8 or higher, running Outlook 2013 or higher, Windows instead controls notifications through the action centre. The default notification display time is 5 seconds, but can be made as long as 5 minutes by changing the message duration (in seconds):
Key: HKEY_CURRENT_USER\Control Panel\Accessibility
Value name: MessageDuration
Value type: REG_DWORD
Source : http://www.howto-outlook.com/howto/newmailalert.htm
