Take a fast look how it works:
Share messages between multiple e-mail addresses
thief can't associate your email with your another accounts
Use proxy-email for independent access for shared accounts
delete recipients, disable proxy-emails anytime
Simply add new recipients to shared profiles
Migration from GMail to ProtonMail is no problem anymore
from privacy violations, aggressive marketing and data aggregations
Enter your real email and invent proxy address to get alias at @proxiedmail.com which allows you to receive emails without showing your real email.