@schmittlauch How do you send someone an email? Either you have that person "bookmarked" in your addressbook, or they were part of the addressing in that conversation (by introduction)
I have some more in this unfinished document https://github.com/cwebber/rebooting-the-web-of-trust-spring2018/blob/petnames/draft-documents/making-dids-invisible-with-petnames.md