Like the war on terror — though I don't have high hopes for this analogy making it beyond the opening sentence of today's column — the war on email is now about a decade old. Recently, I've noticed a hard-headedness creeping in: gone are the ingenious tricks for staying on top of it all, replaced by the frank acknowledgment that sometimes you can't. The website five.sentenc.es, for example, urges you to announce "a personal policy that all email responses... will be five sentences or less", and earlier this year Chris Anderson, organiser of the TED conferences, proposed several new rules for email, including the use of "NNTR" — "no need to respond" — as an act of generosity towards overburdened recipients. These are welcome developments, since the curse of most productivity advice is the assumption that, given the right techniques, you can fit it all in, when to be honest, who knows? But my unscientific surveys of email-deluged friends suggest this isn't the whole story. On the rare occasions I'm permitted to inspect these bursting inboxes, one thing’s clear: half of what's in them shouldn't be there at all.