If the fax recipient is reporting that they are receiving faxes with white text on a black background, there are several configuration settings to check or change.

Check to see if the file produced is a reverse image (the path to the fax archive directory is in Setup - System - File Locations)

• If it is reversed, in SPM go to Setup - System - Global Fax Settings and check on the option to Reverse fax image.
• If it is not reversed and you are using GoFax to send the faxes, it is likely that the image is being changed by the GoFax system.
  Go into the GoFax account - Send Fax Settings - General and make sure the 'Use Local Conversion where possible' is checked ON.