If you are using Microsoft Outlook with either Exchange Server or Office 365, you may at times see few emails titled “Synchronization Log” as Unread mails. I have been getting this for years now and it is a known harmless issue and can be safely ignored.
If like me having Unread mails bothers you, you can do this simple fix. To correct it the user needs to customize the search folder as following:
– Go down to Search Folders
– Context click on the “Unread Mail” folder and choose “Customize “Unread Mail”
– Click on Browse
– Unselect the checkbox for “Search subfolders”
– Select manually all folders you would like to see Unread mail from
– Press OK and OK again.
More details here.