BrowserID works by default with email but it has absolutely to dependency on email. It uses it for namespacing and bootstrapping, but nothing else. So foo@bar.

BrowserID works by default with email but it has absolutely to dependency on email. It uses it for namespacing and bootstrapping, but nothing else. So foo@bar.com may or may not have any MX records, all that is required is that bar.com can provide an assertion that you control foo@bar.com. The way bar.com determines that is entirely up to bar.com, it can be a password, smart crypto card, local kerberos or Windows auth, 3-way auth involving your cat Rufus, etc... https://developer.mozilla.org/en-US/Persona/Protocol_Overview https://developer.mozilla.org/en-US/Persona/Protocol_Overvie...