Your Outlook is working fine throughout the day, but all of a sudden you notice there is a mail icon (envelope) on the task bar but your inbox shows no new email. How is that possible as the mail icon only appears when there is a new mail?
The most common reason for the mail icon to appear when there is no new email is when the computer goes to sleep and then wakes up. This causes a minor glitch in the system where the mail icon keeps showing up.
How to Remove the Outlook Mail Icon from Appearing for No Reason
If the mail icon is really annoying you, there are couple of ways to get rid of it. The simplest way is to close Outlook and restart the program. This solves the problem immediately.
The second way is to send an email to yourself and reading it. This will get rid of the new mail icon.
The third way is to right click on the new mail icon and selecting Hide Envelope. This method is not recommended as it will turn off the icon altogether, even for future new mails.