Note that it seems some details of the spec have changed since the blog post was written, so the linked blog post is slightly outdated/lagging behind the actual

Note that it seems some details of the spec have changed since the blog post was written, so the linked blog post is slightly outdated/lagging behind the actual spec document here: https://man.sr.ht/~bitfehler/m2dir/ https://man.sr.ht/~bitfehler/m2dir/ (Which I discovered when I ran into this project yesterday.) via conversation on the mailing it seems there are currently two WIP Rust crates/libraries being developed to implement the spec--one by the primary spec writer & another by an "email-interested" :) 3rd party, developed independently (AIUI) in part as an exploration of library API design space.