Messages not being marked as read after being opened

They are stuck in local outbox. How can I make it smaller?

If it is too large, send it via transferbigfiles.com to [email protected]
Thank you.

I need more direction. When I hit send logs…it auto opens a composed email with the attachments. How can I get to those attachments to zip up and send via a big file sender service?

Log files are saved here: C:\Users%Current User%\AppData\Roaming\eM Client\Logs