Reusing an unfranked stamp - technical question: illegality already assumed!

[NY]

If I receive a stamped letter letter and Royal Mail has inadvertently not franked the stamp to cancel it, it is tempting to reuse that stamp on another letter. I realise that this would be fraudulent and therefore illegal.

But am I right that the barcode alongside every stamp is unique. Does this mean that Royal Mail can check whether they have seen a stamp before and therefore can confirm if it is being used illegally a second time? If so, do they actually do so for every stamp on every letter? Or do they do random sampling?

I ask because I've just received a letter with such a stamp. I've binned it, despite the temptation to save £1.10 by reusing it. But it set me wondering...

[Andrew]

In theory if you peel it off, there are two little oblong windows that get torn off the stamp, preventing re-use.

Also, don't royal mail mark letters with invisible markers as part of their automatic sorting systems, which might identify a re-used stamp anyway ?.

[NY]

I suppose everything depends on whether a letter bypasses the marking machine altogether and therefore escapes invisible (eg fluorescent dye) marking as well as visible black-ink franking. And whether the sorting marks happen to catch the stamp or to avoid it.

[alan_m]

I thought the fluorescent markings applied tho te envelope was more to do with sorting and redirection rather than franking of the stamp.

As other have said there are oblong cut-outs on a stamp making it difficult to peel off and re-apply. I have 20 first class stamps and can see that the bar code is different on each (at least on the ones where a

10 second look the differences can be seen). I assume that they record that they have gone through the system. They may still attempt to deliver the letter but demand a fee beforehand, which may be more than the postage.

[Adrian Caspersz]

It is. I've got a very interesting free app 'Scandit' on an iPhone that reads lots of different bar code formats.

Does

The post office is well used to adding surcharges for the receiver, of non related amounts that will add up to a tidy profit over their expenses. There is no reason for not issuing them all.

[Dave W]

Yes the code is different on every stamp. Whether they store all the codes and block one that they've seen before, is another matter.

[Bob Eager]

It would be easy enough. You only need one bit per stamp.

[alan_m]

Just get the felt tip out and add a random bit to the bar coding.

[Mark Carver]

I received a letter the other day, new barcode stamp, unfranked, and someone had used a biro to stick a cross on it. Often seen that over the years, don't know who does it, but I suspect the postie, so force of habit.

I 'repurposed'  a new barcoded stamp recently, it was on an envelope of a birthday card we were about to send, but the recipient sadly passed away. I just cut the stamp out of the envelope with a 5mm 'border', and sellotaped it to another envelope, one that I was sending an expired driving licence back to DVLC. I wouldn't have done that on anything more personal, it's all rather 'freeloaderish' isn't it ?

(I threw away the birthday card (in the green bin, of course)) Could have tipexed it, and reused I suppose

[Tim Streater]

Plus bits for the code, presumably.

[Bob Eager]

No. Think about it.

[Owain Lastname]

You can cut the front off the card and mount it on a new blank folded card for that 'handcrafted' look.

I've been recycling received birthday cards that way for years.

Regards

Owain

[NY]

There's nothing illegal or even immoral about taking an unused stamp off a letter that hasn't been sent and using it on another one. I would hope that Royal Mail wouldn't penalise people for doing that, and *would* be using the barcode to confirm that the stamp hadn't been sent already. Modern stamps are harder to get off an envelope than old "lickable" stamps because the stamp can't be steamed or soaked off.

The other cost-saving thing I do is to send several birthday cards in one envelope: my sister and two of my nephews were all born with about a week of each other (different years, obviously!) so I put all the cards into a single A5 envelope. It is better to pay for one large-letter stamp than for three normal-letter stamps going to the same address. I once had a post office clerk tell me off for doing it: I think she though that it was my moral duty to send three separate letters and thus boost the Royal Mail's profits a bit more!

[Brian Gaff]

In theory, if what you send can be seen as large print or a ram stick or cassette, then you can post them free first class articles for the blind mail. You can buy labels from RNIB, now whether the postman has to stand there and test your eyes before delivery, is highly unlikely. Brian

[Theo]

I've thought about it. How were you planning to defeat the cryptographic signature that's embedded in the datamatrix barcode?

(although it seems the barcode scanning equipment is not universal in RM's sorting network, so you might get away with it if they aren't scanned. Seems like the Chinese forgers are now producing fake datamatrix stamps...)

Theo

[Theo]

They may have standing instructions to cancel unfranked stamps on their round. Also, apparently not all barcoded stamps are getting scanned at the moment.

Not really, just you picked the wrong size envelope to begin with. I wouldn't think anything of receiving a letter like that. At least the recipient knows you weren't recycling a used stamp.

Happy Birthday^WSympathy ?

Theo

[Andy Burns]

Presume each stamp starts with a unique incrementing serial number before it gets mangled with hashes/checksums etc? just set the bit that corresponds to the ID

You'd have to transfer the stampIDs between sorting centres, but then just "OR" them into the usedstamps block of memory.

Each 1TB of memory would store 8 trillion used/not used flags, that's

1000 years worth of RM deliveries, and not all of those have stamps anyway.

[Bob Eager]

I'm not. We were talking about the RM scanner, not a private one. And how it records the stamps that have been used.

[Bob Eager]

Exactly. A very old technique.

[Theo]

Ah, sorry - you were talking about RM keeping track of which stamps had been seen using a bitfield. The person who suggested editing the barcode was a different subthread. The crypto is why editing the barcode doesn't work, and the server-side bitfield protects against reuse or duplication.

Seemingly they can tell which sheet the stamps came from:

Theo