user31718: The OP_HASH256 puzzle transaction described here was mined in block 211997. But I read that only standard transactions (with outputs one of P2PK, P2PKH, bare multisig, P2SH, OP_RETURN) get relayed. So how did this transaction get relayed and mined?

user5757: "Relayed" and "mined" are completely separate processes and should not be conflated.
The transaction is valid, so it was perfectly fine to mine it (i.e. include it in a valid block).  
"Standard" is a more restrictive requirement, and as you say, this transaction is not standard.  That means that a default version of Bitcoin Core will not relay it, i.e. will not transmit it to other nodes on the Bitcoin peer-to-peer network.  But if the transaction reaches a miner some other way, they are perfectly free to include it in a block.
We can only speculate as to how that occurred in this case, but here are some possibilities:

Some people were running a modified version of the Bitcoin client (or alternative Bitcoin software) that does relay non-standard transactions.
The creator of the transaction sent it directly to a miner, by some means other than the peer-to-peer network.  Some miners or pools have web sites where anyone can submit a transaction.
The transaction was created by the miner herself.


31718: <p>The OP_HASH256 puzzle transaction described <a href="https://en.bitcoin.it/wiki/Script#Transaction_puzzle" rel="nofollow">here</a> was mined in block 211997. But I read that only standard transactions (with outputs one of P2PK, P2PKH, bare multisig, P2SH, OP_RETURN) get relayed. So how did this transaction get relayed and mined?</p>
 5757: <p>"Relayed" and "mined" are completely separate processes and should not be conflated.</p>

<p>The transaction is valid, so it was perfectly fine to mine it (i.e. include it in a valid block).  </p>

<p>"Standard" is a more restrictive requirement, and as you say, this transaction is not standard.  That means that a default version of Bitcoin Core will not relay it, i.e. will not transmit it to other nodes on the Bitcoin peer-to-peer network.  But if the transaction reaches a miner some other way, they are perfectly free to include it in a block.</p>

<p>We can only speculate as to how that occurred in this case, but here are some possibilities:</p>

<ul>
<li><p>Some people were running a modified version of the Bitcoin client (or alternative Bitcoin software) that does relay non-standard transactions.</p></li>
<li><p>The creator of the transaction sent it directly to a miner, by some means other than the peer-to-peer network.  Some miners or pools have web sites where anyone can submit a transaction.</p></li>
<li><p>The transaction was created by the miner herself.</p></li>
</ul>
