The more I dig into Sele, the less likely I want to incorporate something like e-mail to be part of one's core identity. It does provide a failsafe in the event one loses their domain name (has happened to be more times than I've lost my email address) but e-mails can't be easily linked to and don't have explicit profiles that can be discerned from them. Profile discernment is important for portable identities (and allowing URLs to operate as a localized lookup system for the such makes things a bit easier).