As you are no doubt aware, more and more "original" documents (especially email) have never been anything but digital. While it is often recommended or required that such "born digital" documents be stored as received, they can become unreadable over time due to software changes or need to be converted into another format for archiving. Personally; I would like to extract my emails from the email program's database and store them in a way that can be consulted in the longer term.
Converting "born digital" documents to a more "timeless format", such as Tag Image Format (TIF), Text (TXT) or hardcopy, could be argued to affect their evidentiary value. I do know that some government agencies are particularly concerned about document conversion. Does a direct conversion to a recognized archival format actually affect their evidentiary value (or classification) for genealogical work?