If somehow the community thinks this situation is different and it warrants a refund, then as always we have no problem doing it as long as it doesn't open the door to other types of abuse later on.
I think this scenario is somewhat different if the user can indeed provide the correct letter of guarantee.
In the previous scenario, the only thing the user could provide was a signed message from the address he used to deposit. He was unable to provide a private key or a letter of guarantee. This is insufficient for Whirlwind to draw any conclusions, and I was in complete agreement that this could not be the basis for a refund.
In this scenario, the user has stated he can provide a letter of guarantee. Assuming this letter of guarantee is indeed the correct one, it will have a deposit address inside it. If the user can
also sign a message from the address(es) which sent funds to the address contained within the letter of guarantee, I would say that's pretty compelling evidence that the user is telling the truth and does indeed own those funds.
Happy to be corrected if I've misunderstood anything, though.
Sure, but what if the following happens?
What if we refund this user based on the guarantee letter and then we receive another support request from 'someone else' with the same guarantee letter while also having the private key telling us that he doesn't see his balance on Whirlwind anymore and accuses us of scamming? Do we refund that user as well?
We simply ignore the second person?
With the introduction of the ZK based Notes we won't have this issue anymore because the user will be the only person to have access to it, same as now, but the difference is that in the ZK Note case there is no way we can ever do something about it because your deposit will be one of *Anonymity Set value* deposits and we would have no way of knowing if you withdrew already or any other detail. If you lose it, it's on you.
There's a lot of interesting paths we can take with Whirlwind and we will start to discuss about it here in the following days, that was the reason for our lack of activity on the forum. But e-mail support was always working as usual.