In uk.d-i-y Mark Goodge wrote:

Also, the Royal mail website has a page giving details of SmartStamps,
and one of the items is about the barcode. It says about the barcode
that:

All information in the postage mark is encoded into a barcode
which read by Royal Mail sorting technology to prevent the
posting of fraudulent or duplicate items.

I'd be surprised if the Royal Mail sorting offices have instant online
communication country wide. If you use the same SmartStamp for
posting items in several different places will they really catch it?

--
Chris Green