I didn't receive a mail but my advice is always to be very carefully for mails. I never click any link if I don't know that I ordered the mail or was going to receive it from another person. And it's obvious no one would send an Airdrop announcement via mail if you don't registered before.

100% agree! Therefore I don't give my real mail for bounty or crypto issues. Lazy or corrupt bounty managers are a big danger.