[Mimedefang] Greylisting post-data (was Re: [PATCH] filter_data implementation)

David F. Skoll dfs at roaringpenguin.com
Thu May 28 10:26:43 EDT 2009

Jeff Rife wrote:

>>> Based on the full text of the RFCs and not just the examples, "450" 
>>> seems to be a perfectly acceptable temporary failure.
>> I read them differently.  I see 450, 451 and 452 as acceptable after
>> the final dot, but only 421 in direct response to DATA.  (I'm basing
>> my interpretation on RFC 5321.)

> What text, exactly, leads you to that conclusion?

Section 4.3.2:

         I: 354 -> data -> S: 250
                           E: 552, 554, 451, 452
                           E: 450, 550 (rejections for policy reasons)
         E: 503, 554

Based on the indentation, I see the 4xx codes as acceptable only after
"data" (ie, the final dot), while 421 is an always-available escape hatch.
It's not very clear, though, and it's too bad that we on the RFC2821-bis
mailing list missed that. :-(

> But all of the following make sense after "DATA", even though they 
> aren't specifically listed:

I agree, and an SMTP client SHOULD cope with them.



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