Remember that "requesting email" is a completely illogical thing to do in a court if the goal was to see what had been said. Why would any court say "Show us all of the email communications that went through Exchange but don't show us the Lync messages, documents stored in other systems, contents of attachments, etc."
Of course they don't do that. That would be incredibly silly. They request categories like "all external communications", "all internal" or whatever it is they are looking for.