Anyway, their reading of the law lends itself to a requirement to maintain (at least) two copies of a message (one the primary, and others the backups). If there is only one "copy" then it cannot be a backup.
From a utilitarian perspective, most emails I don't need to keep around once I'm done reading them, so any copy is a backup (just in case I need it again, but not because I know I'll need it again). If I know I'll need it again, then the online copy is the instrument of record.
From a multiple copy standpoint, if I don't clear my browser cache, the online form is a backup, (one could "argue").
Does that give you more privacy protection than keeping messages stored with some third party in the cloud? Or does it give you less protection?
Seems to me they're muddying the waters here with a lack of technical comprehension about electronic data transfer and storage.