I understand about the person's name needed in the box but I have some users
who actually want to reply on behalf of someone else but the message come
from them. I've given them the Send As right and this allows them to reply
from the user or from themselves but when they actually click reply, the
"from box" is already populated with the person they are sending on behalf
of. They would like to click reply and the "from box" be empty so that the
mail actually comes from them rather than the user they are sending on behalf
of.

I hope that makes sense; thanks for the quick response.