I would like to see something better too. I know that these low level protocols are all like this but I think at some point the overhead of something like JSON (the quotes, brackets, etc) would definitely be better than dealing with fixed and variable length fields and a lot of regular expressions especially if you want a lot of implementations created to spread a new protocol.
JSON, binary JSON like MessagePack, XML, Protobufs, Thrift, etc. etc., it seems a bit weird to invent a whole new format. Actually two, because the transfer protocol is separate.
Mail transfer has far less performance requirements than, say, HTTP. Plus, their current format still requires per-string parsing, to separate out e.g. your "gender" from your "gender label", whatever that means.
