IEFRA_ — Add clarifying note that alternative implementations for email are possible

For file retrieval I note that for extremely large files it could be inefficient to retrieve the entire file to parse out the SAC to get the meta data and then deny; would spec disallow a smarter file server that returns only the metadata (over the secure bus) as a first step , then only retrieve file if authorized? I believe answer is spec would not disallow this.

This would be an implementation optimization and the flows are only examples

Adding a note to this effect might be helpful, along with this optimization example for email.

Readdress IEFRA-24

Deferred until RTF