Dark text shading appears when pasting into email, hindering corrections

Dark text shading over entire paragraphs nine or 10 paragraphs that I wanna put into an email did put them in an email but the dark text shading makes it almost impossible for me to do any corrections cause I can't see through it very well it comes from when I copy to try to paste in an email. That's where I see the dark text shading which make it impossible to see the text that I want to correct why does this happen and how can I fix it?