For those asking about the transaction being processed without transaction fee, it was possible because it satisfies three conditions: tx size < 1000 bytes, out

For those asking about the transaction being processed without transaction fee, it was possible because it satisfies three conditions: tx size < 1000 bytes, outputs are more than 0.01 btc and priority is high enough. More details here: https://en.bitcoin.it/wiki/Transaction_fees https://en.bitcoin.it/wiki/Transaction_fees