PS: you can use nick for in wallet chat if you want

wallet chat is still testnet only. If you can switch your nickname around, I wouldn't trust the chat.
subway
I was thinking rather than e-mail, if you send a BBP tx with an encrypted message to the public address, then the private key can decrypt the message with the gift card code. I think this is more reliable than e-mail. I tried playing around with sign message and verify message, but it wasn't exactly what I had in mind... but I guess if the message was encrypted in tx and could be decrypted automatically by the right private key holder, the process would be easy.
I can switch my nickname around on Discord or SouthXChange or PM also... Just look at Slovakia's he has 9 on SX.
I'm aware of this problem though, and of course this will be taken into consideration for voting on objects (by using a keypair). I was not eluding to using the chat nickname for anything important. I was really just alluding to rather seeing a distinct list than a bloated list of duplicated wallets. It may still be valuable to engage the POG list for something (like prayer campaigns) or something in the future.