Unless I'm mistaken[1], right now the popup that has multiple emails in it is the part that will eventually become native to the browser itself, so no service should have access to that list of multiple emails.
Each of those emails is instead tied to an identity provider: for example, you might have a GMail address that uses Google as the IdP, while a Yahoo one would use Yahoo as the IdP. But Google and Yahoo don't actually know that you're using multiple emails to login to stuff, they only deal with the emails you register with them.
What happens right now is that Mozilla Persona hosts the JS-powered popup that lets you choose between emails, so we end up with that info. This is for use in the short-term and for older browsers, but long term I think it will shift to client-side only.
[1] I work for Mozilla, but not on the Persona project, so there is a chance that I'm completely wrong. Doh!
When I log into persona.org, it seems to allow me to remove my (currently only) email address by clicking the first blue "Edit" button and then clicking "Remove" next to my email address. So I assumed that, in the future, I might also be able to add email addresses. Sorry if I was wrong about this.
You can add email addresses now, this is just for the bridge, so it allows you to use alternate addresses to log in with. It's not specific to Persona, it's just how they designed the current bridge (which they aim to phase out in the long run).
Each of those emails is instead tied to an identity provider: for example, you might have a GMail address that uses Google as the IdP, while a Yahoo one would use Yahoo as the IdP. But Google and Yahoo don't actually know that you're using multiple emails to login to stuff, they only deal with the emails you register with them.
What happens right now is that Mozilla Persona hosts the JS-powered popup that lets you choose between emails, so we end up with that info. This is for use in the short-term and for older browsers, but long term I think it will shift to client-side only.
[1] I work for Mozilla, but not on the Persona project, so there is a chance that I'm completely wrong. Doh!