The only wallets I have access to are my musicoin account, sumo, decred and monero. I was mining directly to Bittrex and Cryptopia (before the lawsuits) back then. I might have used coinbase for an ETH address but Im not sure.
YES! Thats my old coinbase ETH address but its not the same anymore. Does coinbase change coin addresses? The fourth (4th) transaction on my account was a deposit from ethermine to that old ETH address on my coinbase. Why would it change over time though?
Block 3760606
May 24, 2017
From: 0xea674fdde714fd979de3edf0f56aa9716b898ec8 (Ethermine)
To: 0x7CB5eA7Dc754Da82B49b4E8ac06639b5AB4c4797 (Coinbase)
Value: 1.000120504754992584 Ether
ETH Price $193.03
Coinbase changes address after every transaction as far as I know, but I think the old addresses are still linked to your account only, so in that case, the old address still belongs to your account if you have that coinbase wallet account. I don't think you can sign a message from a coinbase address since you don't own the keys, but if you can prove that coinbase wallet address is still in your hands, (because any amount sent to that wallet should be in your account), your chances for recovering the account gets higher.
this is so. he could generate a report from coinbase that shows that address .
he could show his current coinbase account and deposit a small amount into that eth address. his coinbase account would go up by that amount.
this would prove the eth address is tied to his coinbase account.
if the coinbase account has the same email as his bitcointalk account has. the email would get a deposit notice to his coinbase account.
so this would prove email+eth+coinbase are linked which should be enough to get him the account.
see issues below with all recovery of any stolen account.
but the current owner may say hey he sold me the account in person for a few hundred in cash.
so there is an issue.
btw in every case the current controller of an account can claim this account was sold via cash face to face.
not sure how that is resolved.