Flags in Outlook make it easier for you to return to important messages that require urgent attention. After flagging an email, you can find it using several methods on the Outlook desktop and web apps.
Finding Flagged Messages in the Outlook Desktop App
Sort the folder
- Go to any folder in your Outlook app (Inbox, Sent Items, Drafts, or Archive). Then, sort the emails by clicking the By Date dropdown.
Select the folder. Then, click on By Date. - Under “Filters,” choose Flagged Mail. This will automatically display all flagged messages in that particular folder.
Select Flagged Mail under “Filter.” 
List of all flagged mails in the Inbox folder.
Check the Task Pane
Select the Task Pane icon on the bottom-left of the app. This displays flagged messages across all of your folders.
Create a Search Folder
- On the left pane of the app, right-click on Search Folders. Click on New Search Folder.
Click on Search Folders. Then, select New Search Folder. - Under “Reading Mail,” select Mail flagged for follow up. Then, hit OK. This creates a new folder with all your flagged messages, both sent and received. Anytime you flag a new message, it automatically appears in this folder.
Choose Mail flagged for follow up. Then, click on OK. 
Go to For Follow Up folder under Search Folders to see all flagged emails.
Use instant search
- In the top ribbon, click Filter Email under the “Find” group.
- Select Flagged. All flagged messages across all folders will be displayed.
Select Filter Email. Then, click on Flagged. 
List of all flagged emails in the “Search” tab.
Finding Flagged Messages in the Outlook Web App
- Sign in to outlook.com and navigate to your folder of choice (Inbox, Sent Items, Drafts, or Archive).
Go to your folder of choice. - Click on Filter on top of the email list. Then, select Flagged from the dropdown menu. This will display all the flagged emails in that folder.
Click on Filter. Then, click on Flagged. 
List of all flagged emails in the Inbox folder.