Here we are, 12 years later, and there is still no real answer to this question. I can tell you this: I occasionally get packages from a certain eBay seller who mails everything with stamps (as opposed to a preprinted label) and the packages always arrive with no cancellation on that postage. And when desperate for an extra stamp once or twice, I have removed one of those stamps and placed it on an envelope that I have then sent, and everything has always arrived at its destination as anticipated. I didn’t fake these stamps— they were real stamps. But there was no automated cancellation of them once they were used the first time. So while the Post Office may be able to detect a real stamp from a fake one, as of 2018 it is unable to detect a used stamp from a new one if not canceled with a rubber stamp or postal ink pen of some kind. Which is sort of relevant.
I know this is a zombie thread, but chances are, that stamps.com paper is coated with the identifying chemical.
On your home printer?
Way back in the early '70s, when I was an Art Director, I did a special job from a wealthy client. The man knew that, at the time, I collected Japanese postage stamps. In appreciation, he gave me a set of maybe 20 very early Japanese stamps. I happened to own a book that described all known Japanese counterfeits… sure enough, they were all fakes; there were tiny discrepancies in every one. But they were beautiful fakes. I may still have them around somewhere.
Each stamp that is printed from stamps.com has a unique 2-d barcode.
Seeing this post pop up again reminds me of something I forgot to mention last time. In the mid- to late 1990s someone published a book that showed (or purported to show) fake stamps that were successfully used to post letters in Canada. The fake stamps were skilfully designed, resembling contemporary Canadian stamps and also the older engraved variety, but were obvious parodies for anyone who took the time to examine them for a few seconds. I remember, for example, that there was a stamp featuring Preston Manning (then the Leader of the Opposition and a frequent target of jokes and impersonations on sketch comedies). The book presented photographs of envelopes bearing cancelled versions of these stamps.
I can’t remember the title or author of the book, but if anyone knows, please enlighten me. I wouldn’t mind getting a copy to see if I can determine whether the cancellations were also fake, or whether the author really did send them through the mail.
It’s a matter of cost effectiveness, really. Is it worth spending, say, $10 million on security measures in order to catch $5 million worth of fraud?
I know this is an old thread, but I’m wondering if it’s fair for the OP to identify the USPS with “the government.”
But the OP doesn’t make this identity. They ask how the government identifies USPS stamps. Postal fraud is the purview of the US Postal Inspectors, a federal law enforcement branch. (Even so, is it really so wrong to casually refer to the USPS as “the government”? It is an organization mandated by the constitution and established by the government, even if they have a fairly hands-off approach to running it.)
I’m curious about this too. I’ve received a few letters with no visible cancellation stamp, so what’s to stop me from peeling it off and reusing it? Could the USPS be using ultraviolet ink or something else that’s not visible, or is this just a goof, like their stamper ran out of ink?
Decades ago I read that the technology was so simple that you could mail a package with a $0.10 stamp and it would go through because the machines recognize the phosphorus on the ten cent stamp, but weren’t smart enough to be able to count how many there were. It was also noted that stamps for $0.01 or $0.05 did not have the phosphorus on them.
Let me know how successful you are in trying to remove a self-adhesive stamp from an envelope.
It’s not so hard if the stamp doesn’t have those annoying perforations in the middle. In fact, I think it’s easier to peel these off than the regular non-self-adhesive kind. Are all self-adhesive USPS stamps perforated in the middle now? I know that the definitive Machin stamps of the UK are, which is too bad because I get an awful lot of mail from the UK with uncancelled stamps. I’ve yet to see any self-adhesive German stamps with the perforations, but Deutsche Post almost always cancels stamps.
I know what you’re talking about (I’ve also seen it on Machin stamps), but I don’t think I’ve ever seen that feature on a US stamp.
A couple of citations in support of the point already made by psychonaut above:
No but what we stopped doing is adding a water soluble layer between the self adhesive material and the actual stamp. The first generation of self-adhesive stamps could be soaked off the envelope with warm water without any damage to the stamp. Theoretically, if one received a letter where the stamp had not been cancelled, it could have been soaked and reused with the “cheater” using their own glue.
Current stamps will not soak off.
There are several ways to “cheat” a stamp especially if you are sending snail mail to a friend.
Stamps can be considered legal tender for certain debts and can be used to pay IRS tax debt.
Which debts would those be?
IRS tax debt. He just told you.