Same as David, I don't trust online "storage" services. Most or all will use your data for whatever purposes they want (starting with marketing, but if someone were to pay them enough I'm sure they'd sell it). I use USB sticks to carry stuff around, or upload it to my own webserver and download it again from whereever it's needed.
of course you should not use services like gmail for those emails as they're stored externally (and in case of gmail by a company that reserves the right to use the content of those emails for whichever purpose they choose and actually do so).
A USB stickdrive (encrypted if you like) is the best option.