Does "subject error" mean the error in the subject of your message? If so,
then note that it often does not work to use the subject to describe the
problem. The subject should indicate the problem, but the problem must be
fully described in the body of the message. In my experience, anyone that
uses the subject to describe the problem does not explain the problem
adequately enough to get a useful answer.
As Gary said, copy the entire error message from Windows Mail and paste it
in a message here.