Yeah, this is a tough one. You can't just have random people saying "please change this email for another person" without permission, on one hand, but you violate other codes if it's clear you send med or financial info to the wrong people. That's why you get so little actual info in emails from bank and medicals these days.

But without a confirmation process to verify correct emails, this will continue as a fact of life, just like wrong phone numbers in the last generation, and wrong postal addresses in the gen before that.