Anne McElvoy: Don’t trust emails, just head to the pub for that confidential chat

It could happen to any of us. You email one of the most powerful women in the world, sharing your heartache at a family feud. A few years later someone publishes Hillary Clinton’s personal emails, and with it what it feels like to be elbowed out by a less electable brother becomes common property. David Miliband is the latest public figure to have shown an antiquated faith in emails remaining private, when they have a disturbing habit of leaping out of the digital undergrowth.

You don’t have to be an Ashley Madison devotee to see that many more confidential emails reach the wider world than those who typed them thought possible. From the newspaper hacking scandal to Fifa’s woes and Sony’s leaked messages about the tantrums of mega-stars, privacy on the internet has turned out to be subject to more qualifying clauses than an insurance contract. A new book, Cyberphobia, by Edward Lucas, points out how often supposedly secure systems can be full of holes — and even complex passwords provide no big obstacle to anyone intent on getting round them.

Our growing familiarity with entrusting personal thoughts, deliberations and anguish to email or social networks has been matched by the march of external parties all claiming the right to access them — from government inquiries to lawyers and tax authorities, to say nothing of hackers and sacked IT staff. Quite often, like Mr Miliband, we are not even part of the reason the emails are required — a congressional hearing into Mrs Clinton’s use of private email smoked out those from Mr Miliband, and with them, a lot of old feuds about Labour politics (plus ça change). Now we know Mrs Clinton wants skimmed milk for her tea and watches The Good Wife. As well she might.

We fancy that we tread carefully in our digital meanderings, when really we leave galumphing great tracks and clues in our wake for cyber Sherlocks. The fear of technophobes used to be that as email eclipsed the written letter, historians would lack a cache of information about our motivations, obsessions and fears. But letters were always written with one eye on posterity, whereas emails contain the spleen and focus of a moment. As such, they are invaluable guides to the minutiae of life.

Try looking through your own sent messages of a few years ago and you will encounter a time-shifted version of yourself. Contacts will have faded away like wraiths, only to pop up unbidden when you type in a similar name. You can chart the successful and annoying bits of life from the clues in the subject field; “Meet up?” (early period of optimism), “Following up” (why have you not got back to me?), “Etc” (trying not to look keen, but still chasing).

The rise of unwanted revelations from digital caches makes people less likely to engage in day-brightening exchanges of gossip or banter about the CFO’s new toupee. We find a disturbing number replied to by someone we didn’t send them to — the PA or, worse, a Corporate Affairs department. Faced with these risks, we resort to stock phrases, such as the maddening Americanese of “reaching out”, which suggests saving a drowning man when all we want is a coffee and friendly ear. If we need a confidante, we will have to resort to the prehistoric practice of going down the pub. Heed the lessons of Hillary’s digital depository: emails never die.

@annemcelvoy is senior editor at The Economist