CoinWallet Spam Attack

CoinWallet.eu flooded the Bitcoin network with over 169,000 dust transactions across the summer of 2015, aiming to prove the 1 MB block limit was too small. The July attack drove mempool backlogs to 80,000+ transactions, raised fees by 51%, and sparked fierce debate over spam filtering and block size — a direct precursor to the SegWit and block size wars.