Try using DISM to restore the health of your OS
Dism /Online /Cleanup-Image /RestoreHealth
If you get the missing sources error again, you can add /Source:c:\test\mount\windows if you mount a wim file with dism - make sure the wim matches your OS!
SMTP Server requires .NET 3.5, is that successfully installed? If not, try installing it alone first and see if ...