After reading this question I got interested in these mysterious spammers who sent satoshis randomly. For what I read, here's been plenty of discussion about this, mainly at Bitcoin talk (discussions here, here and here - in Spanish also here, here and here) but also somewhere else on the network (as in here).

I got sad when I saw I hadn't received such micro-payments, doubly sad when I read most of such transfers won't ever be included since most miner pools actively avoid collecting such "dust" - so spammer gets his message out for free, even though it may only last for a short while.

And I wondered - why not do include such dust, so that spammers are harmed economically and stop doing it? Plus, plenty of people would get tiny bits of money.

What would be the cons? Plus, if I've understood how Bitcoin operates correctly, spammers would end up paying much more in transaction fees than the amounts they actually send - which makes it doubly mysterious to me why not include them.

2 Answers 2


why not do include such dust, so that spammers are harmed economically and stop doing it?

I'm still not sure that would be enough to prevent this kind of spam activity. Even if these transactions were committed to the blockchain, 100,000,000 such broadcasts could be made from 1 BTC, that's a lot of reach for $700.

  • Good point! However, the downside of not including them is that after some days pass those transactions die - so from the network perspective it's as though they had never happened, in which case they can send yet another 100 million messages, and then some more... basically for free (since the cost of buying the initial Bitcoin is already a sunk cost)
    – Joe Pineda
    Feb 13, 2014 at 13:16
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    @JoePineda If this actually becomes a problem then most likely what will happen is more and more clients will stop forwarding transactions with less than 5430 satoshis in outputs. Accepting them is completely up to the miners, and they have no incentive to accept something that doesn't pay the fee. Feb 13, 2014 at 18:00

The transaction fees are optional, the sender can choose to include the fees and the miner can choose the include the transaction. Each transaction that is included increases the size of the block which affects how quickly it can propagate and the size of the entire block chain.

So one explanation of why not to include them is because it doesn't profit anyone but the one person that got the dust, and it only profits them a tiny amount. Another explanation is that these total amounts are less than 5430 satoshis, which is the currently accepted smallest possible transaction in the default implementation.

  • Thanks for your answer! But then, your last paragraph begs the question: Since sending a single satoshi is way below that 5,430 low limit: how come these dusty transactions get propagated at all, then?
    – Joe Pineda
    Feb 12, 2014 at 16:43
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    Sorry I should have been more clear, the 5,430 'limit' is just a default in the standard wallet. Other implementations may allow it and repeat those transactions. Feb 12, 2014 at 18:21

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