After identifying the duplicate emails, you can manually remove them. You can view the items in a table and select them by clicking on their category headers. Then, choose which type of
duplicate emails you want to delete
. You can also select the folder that contains all the duplicate emails. If you're not sure what you're looking for, you can use a special program to search for them. Then, you can manually delete them.
See also -
emailspedia.com/how-to-recover-deleted-emails-in-outlook/