Sent emails are not showing up in Sent folder

[lesliegut]

On my new S9, my sent emails are not showing up in the Sent folder. However, if I follow a thread from a message in my Inbox, and click on one of the "sent" emails, it comes up. Not only this, but if I then hit the "back" arrow, I get a Sent folder with all my (previously lost) sent emails. When I go back to my Inbox, then click the Sent folder again, it's empty. So, there must be a hidden "Sent" folder that I can't find. Can anyone help??