F2pool and 1mb spam block

[chalkboard17]

https://blockchain.info/block/000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe
Why would f2pool mine a block with only this transaction? A 1mb spam transaction with no fees.

[unamis76]

Troll much?

Pretty weird transaction, maybe someone has a theory...

[2112]

https://blockchain.info/block/000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe
Why would f2pool mine a block with only this transaction? A 1mb spam transaction with no fees.

It is actually spam cleanup transaction: it reduces the UTxO set by spending 5569 previous 1000 satoshi payments.

If you want to continue an intelligent discussion please lock this thread and post your observations in the dev subforum thread https://bitcointalk.org/index.php?topic=1112943.0 .

[ujka]

It's a transaction to remove spam transactions from full node's unspent UTXO cache.
Long story: some spammer created thousands of spam transactions to bloat the network and the blockchain with outputs so small that spending would go all for fees. He then gave the private key of that address on reddit to fool with the bitcoiners there, but some guy created a script and swept the address. That way he removed all that small unspent spam UTXOs from full node's cache. (full nodes have to keep track of all unspent outputs. forever.)

https://www.reddit.com/r/Bitcoin/comments/3cf6qg/need_help_moving_coins_to_new_address/