Hi. Thanks for the reply. That option you mentioned is only able to be set for incoming emails not outgoing (sent) emails.
I have thousands of emails that I have sent to various companies I deal with and have created a folder for each of them and a rule that moves any sent emails to the correct sent folder. Unfortunately, the emails that are sent are showing up as unread and therefore being included in the unread mail folder.

I hope the above better explains what I need.