how to remove horizontal line in HTML email messages?

[Troy Kilen]

I'm sending HTML email messages in Outlook, and when I
create a new message, the HTML appears fine but with a
horizontal line above it. With most HTML layouts, I'm able
to simply click it and hit delete to remove it. But with
my design using stylesheets, for some reason I cannot
select the line to remove it.

How can I configure Outlook to NOT add that line to every
HTML message I create?

Thanks,
Troy