How did you two come up with this way of doing things?
This may sound a little harsh, but … can your supervisor not simply edit the file in Excel? Does s/he not have Excel? Or has it but doesn’t know how to use it? What’s the barrier to simply attaching the Excel sheet to the outgoing email, rather than dumping the text into the body of the email? I don’t really get how this copy-and-paste process you describe evolved.
