Outlook unread mail folder not updating
Each time a messages is marked as read (manually or automatically), the Syncing Master will update this information for all users who subscribe to this functionality.
This option works for both: shared private folders and folders created directly in the C2Public Folders Folders tree.
There are significant changes to the looks and behavior of the New Mail Alert when you are upgrading to Windows 8 or Windows 10 in the future. In Windows 10 this notification mechanism got extended with the Action Center.
Outlook 2013 and later all take advantage of this notification mechanism and don’t use the New Mail Alert that is being shown when you have it installed on Windows 7.
Any setting longer than 300 will end up displaying the alert for 5 minutes.
Any non-predefined duration will display the option in Settings being configured to display the alert for 5 minutes even though it will actually display it for the duration configured in the Registry.
Which is really an annoying situation, because sometimes other member couldn't know that whether he has read that particular message or not.
To solve this, you can use the action rule; display a specific message in the New Item Alert window.
Synchronization of read / unread status of messages lets users synchronize the status of messages.