The “webxdc.selfAddr” is a bit of an ad-hoc design to leave it to xdc apps whether they sent the identity of users around. But Delta Chat is already itself itself in the business of knowing from where an update comes from, namely e-mail + cryptographic identity but it does not expose this in the “update” struct pased into the Updatelistener Webxdc Specification - Webxdc
Maybe a new “webxdc.selfUri” with a “mailto:…” could be offered but what do you think this would help with?