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Re: rfc2821bis-01 Issue 17: all contination lines must use same code

2007-04-10 12:06:59

David F. Skoll wrote:
Hector Santos wrote:

    Under most scenarios, servers SHOULD use the same reply
    code for each multiline response line when it is going to
    be displayed at the same time. However there are  scenarios
    (Keep Alive Client Timeout issues) where servers MAY use
    "150-" as an alternative reply code in a continuation line
    when the server needs to issue a heartbeat to keep the client
    alive during unsual delayed backend processing:

I don't like that.  There's no reason to assume that parts of a multiline
response will have any effect on the client timeout.  It might not reset
its timer just because it gets part of a reply back.  Maybe many current
implementations do, but that's just good luck.

I believe that a proper negotiated ESMTP extension for "keepalive"
intermediate replies should be developed.  We shouldn't try to hack
something in.

Hi David,

I agree 100% and this issue began a few years back including during the last previous call out for 2821bis discussions where I brought the "Keep Alive" consideration. So John is very aware this isn't a first time discussion. I might just go ahead and write a I-D finally. Back then I had never written an I-D. But with a few under my belt now, I am more familiar with the process and more comfortable writing one if need be.

However, for 2821bis, I just would like make sure that it doesn't pre-empt such new efforts. Thats really all I would like to seek here and thus I go back to my original post to Frank with a suggested text, which was really just a starting point and would be very happy for a documentation person to reword it appropriately:

   Only the final or last reply-code is important in a multiline
   response. The client MUST|SHOULD use the final line as the ultimate
   server response.  It is possible for a server to use a
   preliminary reply code 150- as part of multiline response
   with a final non-continuation completion code.

   For example:

   354 Please Start sending....
       [ client uploads message ]
   150-Please Wait...
   150-Please Wait...
   451 Sorry, Rejected, try again later

I think the 1st and 2nd sentences are just a clarification of what is already implied in 4.2.1 (as you pointed out) in:

   In many cases the SMTP client then simply needs to search for a line
   beginning with the reply code followed by <SP> or <CRLF> and ignore
   all preceding lines.

If this is sufficient, I can agree with that. But I do think it should be highlighted.


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