Yeah, I figured this would be tricky. We are already using IDs as primary keys that are independent of email addresses, so at least that's not an issue. Do we want to support having multiple email addresses associated with account though? That would have pretty wide-ranging implications, I would think. As far as I can tell, so long as we allow only one email to be associated with an account at a time, the only changes that need to be made (beyond this patch) to support changing email addresses is updating the SSA token and email address on the client side once the address has been successfully updated. Allowing multiple email addresses per account would be a fair bit more complicated.