What I really want is a semi-permeable letterbox which simply won't allow free newspapers or blatant direct-mailed adverts to be pushed through it, but will let through proper letters.

Ah, Maxwell, is there any problem you can't solve.

Someone else was pondering this problem, and having difficulty because the paper distributors changed constantly. Perhaps one should hide the letterbox where the postman can find it and ranodm people can't. Or have a really narrow one. Or have a recycling box by the door so getting rid of the paper is zero effort.

Hiding the letterbox: err, how?

Narrow letterbox: mine is already too narrow to fit mail-ordered DVDs through, so if anything I'd like it wider.

Recycling box: I really should get round to arranging to be sent one of those, now you mention it. I currently batch up recycling until it's worth shoving it all in my car boot and dropping it off at Sainsburys on my way home from work.

You should now have a shiny new blue box. Or a scruffy, beaten-up new blue box if it's anything like mine. Apparently they will happily take black box recycleables from a blue box and vice versa.