Sent Mail showing as Unread - How do I change this behavior?

Hello, great email client, thanks! My question is regarding the Smart Folders. It appears that every Sent email gets logged as unread, then appears in the Unread Smart Folder. I do not wish to see sent mail as unread in this view. How can I change this behavior? Thank you.

What mail service do you use? Does it happen to all your sent messages?