[oarsinsync]

Fair, the analogy doesn't hold onto the functions provided, but RFC 5233 is very clear that the user+detail separation does not provide any privacy protections, nor can it.

The 'user' part is still public information, as is what it's used for. There should be no expectation of privacy for information being used per specification design.

The usability trade-off is a shame, but the solution was half-baked at best, and is primarily useful when combined with privacy-sacrificing public email providers. When you have greater control of your email, distinct 'user' parts can be used, which does provide the privacy aspect desired.