My wife and M-I-L have their own Hotmail accounts, whereas I have an Outlook.com account. Now we would like to back up the contents of all three accounts (mainly the e-mail messages) into a single USB Flash Drive, which we can safely store somewhere else.

Could somebody please advise the best way to accomplish this? We would rather avoid storing the messages in the hard drive of our home PC, so that no one else can peek into it.

Thanks for your suggestions,.