Doing that is only legal (under US copyright) if you bought the CD and ripped it yourself. But that's pretty much impossible to validate from the receiving side

Doing that is only legal (under US copyright) if you bought the CD and ripped it yourself. But that's pretty much impossible to validate from the receiving side. Dropbox "allows" for it but they're in a grey area, just like other services have been able to skirt the issue. It's likely to not be a big enough concern for anyone right now to go after that particular use case.