Unread Sent emails


New Email
I have an Apple iPhone 6 Plus using iOS 12.3.1. I have a yahoo and an Att email. Whenever I send an email my Sent folder shows I have a new email. I am not using CC or BCC. If I go to my HP Desktop and login to my email it also shows the same thing. If I send an email when I am logged in on my desktop, I also have the same problem. This happens on all my emails sent out. How do I fix this so that it stops showing my sent mail as an unread email? I do not use Outlook at all. I have Windows 8.1 but had the same problem with Windows 7. My iPhone is setup using the correct input and output criteria. Authentication password. Server Port 465. I have tried deleting and re-adding my email. I have SSL set on.