This former Secretary of State needs no intro. Whatever or whoever you believe - whether a foreign government compromised her mail server, or whether the whole story is just a smear - this former first lady did run a "shadow" mail server to store sensitive emails, and this was not protected by a security expert. A billionaire who is president of the Indian National Congress also had a private mail server breached a few years ago.

You may wonder what is wrong with Google Mail, Hotmail or Yahoo Mail. With mass market email free services, you are the supplier, not the customer; data is harvested ("anonymised") and adverts are shown relating to your emails. Imagine going into a pharmacy for some embarrassing medicines and then seeing adverts down the road targeted at you. This is what they do. These providers do not offer great authentication, antivirus/antispam, and often come with a “forgot password” loophole. And yet, your email address is the key to your private world.

So what are the lessons to be learnt? If you do not know how to run a mail server securely, don't or get help. Use a service that does not contain loopholes, offers defences against password hacking, and makes use of every trick in the book to defend against general and targeted viruses.