I do.
I have all of my domain e-mails dump into my gmail account. That way should I get someone sending me files, viruses, and alike it will take down Yahoo/Hotmail/Google before it takes me down. They have all the spam blocks, virus updates, and so forth.
I've done it the other way, but I do not want my personal e-mail used for business. I prefer only close friends and family have that one. Helps me prioritize better on my end.
