"an SMTP response consists of zero or more lines which start with a
three-digit number and a hyphen, and then exactly one line which starts
with a three-digit number and a space". How many people think that's
2821 says the space on the final line is optional. "250" CRLF is permitted.
Since every SMTP server I've ever seen sends the space and some text, it
seems reasonable for 2821bis to say something like "servers SHOULD send
accompanying text, not just the three-digit response code". I do not
have a strong opinion on the subject, however. Does anyone else?