Are we talking about data being shared across services or spammers? Spammers play by different rules because they can just generate infinite email addresses on

Are we talking about data being shared across services or spammers? Spammers play by different rules because they can just generate infinite email addresses on the fly and not have to worry about storing them unless they get a hit. I would consider that a different vector than your legitimate email address being shared. In my experience, a private email domain is a neon sign for spammers. I would never recommend a private domain for privacy or anti-spam reasons.