Black text on black background

We are seeing a few members use Word etc. to create their post. This causes a problem, as we use a black background for the Forum. Is there any way to check for black coloured text and dynamically change it to the default colour. Black is not available as a text colour on the dropdown for forum posts, so there must be a code being used for posts copied from Word. We have enabled the IE forum posting text editor.

Look forward to your suggestions.

Vin