Meanwhile I have my own Chase account. Chase's system happily sends emails for both accounts (mine and this other person's) to my email.
I have called Chase twice, explaining that a) sharing another customer's information is not good and b) this is why nearly everyone requires email confirmation (Chase does not). But both discussions, including 1 with a supervisor/manager, led to them firmly saying that it is impossible to stop, since apparently this other person accidentally typed my email as their own. (I also suggested that they simply contact this other person; apparently this is also impossible.)
Any advice on how to escalate this?