We follow the same protocol, and we are interoperable with Russell's implementation as well. The only differences you'll see are in the actual implementation, working and reliability of our services.
Having said that we do have a lot of features on top that are extra like WKD PGP encryption implemented on top of nip-44, and domain routable mails ofcourse. I'm not sure if NMail has it, but it'd be awesome if they do!
1
