Email crypto spam is the big problem. Only special email address for crypto could solve this problem more or less
This will solve the issue, Bounty hunter should not use there personal email when joining in bounty campaign. Always expect the worst that there details will be exposed in public.
Bounty manager submit all the spreadsheet information to the project owner so even though they hide it. Project owner will see it and they are the one that selling or giving away user email to other project to have initial user for them.
That what possibly it takes, they can sell it in the black market. A reason that I won't make any participation when asking email addy and I suggest for hunters not to do as well because this also risking our personal identities 0r possible ruin.
I can't imagine if someone, a uniform personnel will bring you to their office for interrogation for a crime that you never know. That possibly a worst-case scenario that I am afraid of.
We don't know the reason why asking for such important information and if we care about ourselves, should we have not to do this.
Bounty managers also will have to think about this as well and for the welfare of their participants unless you are to have a bad intention.