[Top] [All Lists]

Re: DISCUSS and COMMENT: draft-ietf-sieve-refuse-reject

2008-11-17 14:09:27

Less verbose, previous paragraph for context:

   This document also describes how to use reject/ereject at varying
   points in the email stack: Mail Transfer Agent (MTA), Mail Delivery
   Agent (MDA), and Mail User Agent (MUA). See [EMAIL-ARCH] for a
   comprehensive discussion of these environments.

   This document also specifies the use of a Delivery Status
   Notification [DSN] instead of an MDN when appropriate. In general,
   an MDN is a human-oriented status, generated by an MUA, while a
   DSN is a machine-oriented status, generated by an MTA.

On Mon, 2008-11-17 at 08:06 -0800, Aaron Stone wrote:
On Fri, 2008-11-14 at 13:54 +0000, Alexey Melnikov wrote:
Hi Pasi,
My apologies for the delayed response:

Pasi Eronen wrote:

The document says the main difference between 'reject' and 'ereject'
is that the latter allows SMTP/LMTP level rejection (and there are
some details about non-ASCII strings).  I think I understand this
part, but it seems there's another difference: the former talks about
sending an MDN, while the latter sends a DSN.

Correct. I would consider MDN versa DSN to be a minor difference.

I'm not that familiar with the distinction between MDNs and DSNs (and
on first reading, thought they meant the same thing),

They are very similar syntactically. Semantically, DSN is for reporting 
delivery status (don't involve a human), while MDN is for reporting user 
processing status, such as message read, deleted without reading, etc.

and I think the
document would benefit from short description here, reminding readers 
that they're not the same thing, and explaining why 'reject' and 
'ereject' do things differently.

The reason why MDNs were chosen in the first place, because reject 
action could be implemented in a Mail User Agent. The MUA is not allowed 
to generate DSNs, because the message was already delivered to user's 
mailbox. At this point only MDNs can be generated.

What happened after RFC 3028 came out was that many more Sieve engines 
running inside MTAs or MDAs were developed. For them, generating MDN 
might be a bit awkward.

So I am not entirely convinced that stating this difference is going to 
be very useful. Please let me know if you still think otherwise.

I accidentally left an editor's mark in the -08 draft I just posted, and
mis-attributed the sentence above as [[[arnt's text]]]. I wanted to
possibly put this into the document to describe the difference of MDN
vs. DSN.

Proposed text:
   This document also specifies the use of a Delivery Status
   Notification [DSN] instead of an MDN when appropriate. In general,
   an MDN is generated by an MUA or MDA, and can be used to indicate
   the status of a message with respect to its recipient, while a DSN
   is generated by an MTA, and can be used to indicate whether or not
   a message was received and delivered by the mail system. In other
   words, an MDN is a human-oriented status while a DSN is a
   machine-oriented status.

I'll flip the location of this paragraph in the introduction wrt the 
paragraph that introduces the reference to EMAIL-ARCH so that MTA, MDA and 
MUA are already defined at this point.

Like it? Dislike it? Don't care?