Since you moved to this website, the Rust mailing list got decommissioned. Sadly, you can still subscribe and post using it. The automated reply, I quote:
The rust-dev mailing list is no longer active. Please direct your
queries to http://discuss.rust-lang.org/
leads users to a website that does not exists, furthering confusion.
Thanks for the heads-up! I informed infrastructure team and we will get this fixed. With RustConf coming up and the impending release of a new compiler next Thursday, I'd expect that to take some time, though.