Webfist

 Webfist  was software used to run a distributed fallback network to enable webfinger on email address from providers that do not yet support webfinger. It was first implemented during the 2013 IndieWebCamp. The http://webfist.org domain is not working as of 2023, but more information can be found on the last archive in 2016.

An overview of how it worked can also be found at Brett Slatkin's blog:

The brainstorming session page from 2013 also has links to some information: WebFinger Past Present Future