Had same problem - with ghost emails that I could not delete and got unknown
error. I saw an earlier post that was "readable" and tried it tonight.
first - turn off scan emails in your Virus program
Close windows email
open task manager - processes Tab: end porcess for Winmail.exe Applications
Tab: end Task
Go to Start, All Programs, Accesories, Windows Explorer, Computer, Local
Disc (C), Users, Your name (or whatever you called yourself), AppData, Local,
Microsoft, Windows Mail.
Copy the whole Windows Mail folder to a disc or another location (desktop etc)
You may want to rename this file Windows Mail 2 (this is in case something
goes wrong)
Go back to original windows Mail Folder (see above - the one you just
copies) and locate the file named WindowsMail.MSMessageStore Delete this
file. Then delete the same file in the BackUp folder.
Close all windows and restart the computer.
The ghost email was gone. I was able to send, etc.
This worked for me. Hope it works for you......
And thankyou to Bernice who discovered this fix.