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Re: New Issue: NOOP clarification

2007-11-29 11:54:57

Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu wrote:
On Wed, 28 Nov 2007 17:39:13 EST, Hector Santos said: NOOP (NOOP)

I just came across a transaction where a Microsoft ESMTP server rejected it with a 421 response.

There's 2 cases here:

1) It's trying to tell you "421 It's nap time here".  In this case, it's a
totally legitimate reply - and I've even seen systems that keep a hot
connection open to recent/frequent destinations that intentionally send
keep-alive NOOPs specifically to reap 421's and unexpected closes from the
other end.

2) It's a bug, and somebody needs to learn to put down the crack pipe before

No change to the RFC is needed for the first, as it's working as designed.
No change is needed for the second, because we can't legislate entry into
substance abuse programs in an RFC.

It is possible to have semantics that are independent of whether's a bug, proxy or not? Just like the rest of the document.

I caught it during a teleconference where we exchanging emails, so I didn't have time to look at any details other than note that it SHOULD had not happen, so bug or no bug, I felt, at a minimum, a small clarification needs to be added to hhelp clarify and codify existence practice.

The exchange was this:

C: NOOP WCSAP v2.09 Wildcat! Sender Authentication Protocol
  S: 421 5.5.2 Syntax error (command line too long)

Now here are the facts:

a) it wasn't too long,
b) it didn't ignore the STRING per RFC.
c) NOOP is a requirement
d) The RFC recommended response is 250:

   For example, a command such as NOOP, whose successful execution does
   not offer the SMTP client any new information, will return a 250
   reply.  The reply is 502 when the command requests an unimplemented
   non-site-specific action.  A refinement of that is the 504 reply for
   a command that is implemented, but that requests an unimplemented

e) 421 was not appropriate for the command nor its "string reason"

     421 <domain> Service not available, closing transmission channel
        (This may be a reply to any command if the service knows it
         must shut down)

and so and so on,

So it doesn't matter any of the above or if a proxy or not. Obviously some SMTP servers are not following the recommmendations. Obviously some are buggy. It doen't matter of who was right or wrong.

A clarification should be adjusted into NOOP statement to help future and current implementations update their codes.


Hector Santos, CTO

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