I've done exactly they same for many years via email aliases in MS Exchange. I too discovered that the only real sharing/leaking of email addresses was my payp

I've done exactly they same for many years via email aliases in MS Exchange. I too discovered that the only real sharing/leaking of email addresses was my paypal and ebay ones, and a legacy one that I used to use on USEnet back when we all didn't know better. My take-away was: always proxy ebay/paypal accounts behind another mail provider, and be ready to change those emails when they get compromised.