• The problem stems from the Outlook App wrongly filtering email, resulting in an unread email showing up in Outlook that you can't find. To find and delete/mark as read this one pesky email, you'll have to go online and search through your emails.
• Go to the View tab and then to the View settings.
• Select Conditional Formatting from the drop-down menu.
• To choose the rule Unread messages, click it, then click the Font button.
• Select a typeface, font style, size, and colour to make your unread emails stand out in your Inbox.

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