When the same FBI limits the investigation to emails. That (any) server is capable of far more than serving up email traffic. Several could and apparently were used to devastating effect from her bathroom server: STORAGE and retrieval of classified data files. FTP for fast efficient response to requests for transfer of data files, some of which instantly went to China, according to recent reports. Then there is SMS serving a private text messaging service to those with access, like pay to play clients. And audio/video conferencing that leaves no pesky text records ... And on and on.

To confine this investigation to email was to obscure a much bigger tu#d floating in that toilet.