the easiest and quickest way to get rid strange formatting when doing this sort of thing is paste it into notepad first and then copy it again from notepad.
At http://www.papercut.com/emailStripper.htm you can download a small free utility called emailstripper. This also takes out the funny forwarding signs etc. When you paste it into a new mail after 'stripping' you can format size, colour etc. as usual.