Overall this sort of redaction smells like legal advice.
You define the record as the body of the message and archive messages without the headers, or at least without the sender and recipient headers in them. This might even be a valid interpretation of the US records act.
When asked why you can say this was the archiving policy and you stored the messages as a document and the headers were irrelevant since they did not hold any information.
When asked about who sent or received a specific email that has been redacted you can 'honestly' claim "I do not recall".
Overall this is pretty much exactly the borderline illegal narrative that a good legal counselor would provide in this case.
Of Course that advice was granted based on the premise that there would not be a trail that would make this look premeditated and suspicious.