Why is eminem called eminem yes?

When he started out, his name was M&M, because of his name; his initials are M.M. Mars Inc. (the makers of m&ms) threatened to take legal action if he did not change his name. So he changed it to spelling M&M out; Eminem.

Fun Fact: If you spell "Eminem" backwards it says "men in me". He has three personas: Marshall Mathers, his birth name), Eminem, his stage name, and Slim Shady, the alter ego to Eminem. Ironic, huh? No one knows if he has noticed, but I'm sure he has and it wasn't intentional.