How much would you pay to pore over the emails of a major writer? Perhaps it would depend on how famous they are, how much you liked their books, and how likely they are to have made ungenerous remarks about other writers whom you like a lot less. But if it’s the email of the poet, Wendy Cope, that you’d like to trawl through, you can put your cheque book away, because the British Library has paid up for you. They were so keen to get their mitts on her archive that they handed over £32,000 for the largest electronic acquisition in their history. It comprises some 40,000 mails – ranging from those which are, by Cope’s admission, ‘not interesting at all’ to those which are so controversial that they will be stashed in a ‘classified’ file.

And while some historians will doubtless wring their ink-splotched hands at the loss of lavender-scented lovers’ letters and the sturdy Basildon Bonds of affairs of state, this is surely the future of archives. When even the poets have switched to email, you know the end of the letter has come.

But actually, we should be cheering this development. Formal letters, written in pen and ink, give us real insight into the character of an author, thinker, or politician. Collected letters can often be the paciest books I read all year. But the formality of the letter means that we are usually still getting the writers on their best behaviour – even seemingly informal letters, like those between the Mitford sisters, were written with half an eye on future publication.

But email isn’t like that at all. It can be formal, but it usually isn’t. Even business dealings become less formal in a message which begins, ‘Hi there’, rather than ‘Dear Madam’. Email isn’t really writing at all, it’s frozen speech. The best emails can be almost heard, rather than read, the punctuation acting as timing, so senders can capture their voices completely.

The hardest thing for biographers and historians to reconstruct is the everyday lives of their subjects. Big events – legal trials, parliamentary debates, royal successions – tend to be documented well. But the small events and minor dates are often lost, and with them go plenty of influential, but not documented, figures of the past.

We may despise the banality of Facebook updates or Twitter feeds, but social historians of the future will be incredibly lucky to have a resource which tells them exactly how ordinary people lived and worked. They’ll be able to tell what kind of impact political, legal or military decisions had on ordinary people, not just from newspaper reports of marches or riots, but from those participating themselves, and not in hindsight, but as it was happening.

The same is true of visual records. We used only to have photographs of the most important occasions in people’s lives: their wedding day, for example, or a family portrait after the birth of children. Then cameras and film became cheaper, and we had more pictures, of holidays, or day trips or parties. Then film disappeared and cameras became part of our phones and our ordinary lives. So, yes, future historians will have to dig through a lot of pictures of cats doing something adorable. But, as they head to the good stuff, they’ll have learned on the way how much we loved our cats.

The preservation of email archives is exciting because it conserves the verbal equivalent of these pictures: yes, there will be a lot of iTunes receipts and Amazon confirmations and the rest. But there will also be a sense of who the writer really is, in their most informal and unguarded moments. Where our letters showed us in our best frock, smiling for the camera, our emails will show our underbelly – our peeves, our crushes, our irritations. I am, of course, prepared to sell mine to the highest bidder. They’re full of ungenerous remarks, but so long as you wait until after I’m dead, you can publish, and I’ll be damned.