This is the reason why i have many alternative emails for some airdrops.
Having a referrals in airdrop is not bad, because sending referrals to others is like putting an effort for you to gain such profits. If you feel that an airdrop is not legit or scam, then you shouldn't put your time to this, it's just a waste. To avoid phishing or hacking, be careful where you put your private keys of your wallet. It is important to have emails that is for bounties only to secure your accounts.
Take note: Phishing and hacking is not really a problem 'cause form and registrations doesn't require private infos of your accounts or wallet so maybe you can conclude that this is a scam if this kind of case happens to you.