Is it safe to refund to (one of) output address(es)?

[Stn]

Imagine you got bitcoin transfer which you want to refund. For certain reasons you can't contact payer. Is it OK to pick originating bitcoin address (or one of them) and send bitcoins there? Won't these bitcoins end up somewhere in limbo?

[dillpicklechips]

Depends on what they used to send it. If it was BitcoinQT its fine or even blockchain.info. But if they sent with inputs.io they won't get the refund. Since you don't know its probably better not to risk it.

[maaku]

No. Don't do it. Give them an authenticated mechanism to request a new payback address.

[gmaxwell]

It is _never_ fine to assume this. You should get a refund address from the user.

[MRKLYE]

It is _never_ fine to assume this. You should get a refund address from the user.

I fully agree with this

[b!z]

If the address is one time use they might not be able to access the coins.