DebugMailPlugin issue/Error when sending mail templates


currently having an error when sending mail templates, always getting the error message " Could not find a part of the path 'C:\Windows\system32\%Temp%\XXX.eml'."

I removed the DebugMailPlugin (and restarted the jobservice), and there is no reference in the process chain to a path, but the error still occurs.

Currently on 9.0.

What's the issue here?