John C Klensin wrote:
Well, it's not just 1yz that worries me. It's differing reply codes
in a multiline reply. As Tony Hansen pointed out, there are SMTP
implementations that do not simply use the last reply code, and
although their quality may be in question, they are in widespread use
and breaking them is not a good idea.
There's no quality issue here. As you yourself have pointed out, the
specifications are pretty clear that all the codes are supposed to be the same
and multiple acts of creative reading are needed to support any other
conclusion. And someone else has pointed out that using the first code can
simplify implementation. So: The standards permit use of the first code and it
can be simpler. Seems like a reasonably high quality choice to me.
+1. Very high quality!
Since we have so many high quality 821/2821 "broken" software now, and
the censensus is a MUST for persistent reply codes, John might as well
change the ABNF to support ignoring continuation lines and just use the
first line reply code.
Reply-line = Reply-code [ SP | "-" text ] CRLF
That way EXIM and SUN can claim 100% SMTP compliancy!