Subject: Example extension action

From: Chris Newman <[email-masked]>
Date: Mon, 17 Nov 1997 14:26:08 -0800 (PST)

Here's an example extension action that raises an interesting question:

The action is called "denyMDN".  Based on: draft-ietf-receipt-mdn-06.txt

If the message has a "Disposition-Notification-To" header which matches
the envelope sender, then this will send an "automatic-ation",
"MDN-sent-automatically", "denied" MDN notification and remove the
"Disposition-Notification-To" header from the message.

The interesting question is: are Sieve scripts allowed to edit the headers
of a message?

		- Chris

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From: Tim Showalter <[email-masked]>
Date: Tue, 18 Nov 1997 15:58:08 -0500 (EST)

> The interesting question is: are Sieve scripts allowed to edit the headers

Sure, why not?

The only problem I can see is that in IMAP messages are essentially
immutable so that once the delivery agent had written to the message store,
it's never gonna change.

-- 
                                           Tim Showalter [email-masked]

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From: Tomas Fasth <[email-masked]>
Date: Wed, 19 Nov 1997 16:16:29 +0100

> "Disposition-Notification-To" header from the message.

Nice thinking, Chris.
However, it seem to me quite counter-productive to do a thing like that.
When we finally can see MUAs arriving on the market that supports MDN
(we
aren't there quite yet) you start providing not only tools that
nullifies
those developments, but also automates MDN submission on behalf of the
user
for each message containing the D-N-T header?

Also, as I mentioned in another letter, I am leaning towards the
position
that MTAs should keep hands off MDNs and leave such handling to the MUA.
If your MUA is not supporting MDNs, then why not just ignore such
requests?

A question: Should MTA and MUA responsibilities be mixed up in a single
tool
like a Sieve interpreter?

> The interesting question is: are Sieve scripts allowed to edit the headers

I hope not. Otherwise, you will easily end up with a situation similar
to
sendmail installations, where you easily loose control over what headers
are
rewritten (or deleted, help me ***) and why.

Frankly, I don't understand why a filtering language should be able to
rewrite message headers at all?

Morphing filtering tools into censoring tools have bad vibrations.

-- 
Hälsningar/Regards

Tomas Fasth <[email-masked]>
Tel: +46-13-218-181 Cel: +46-708-870-957 Fax: +46-708-870-258
EuroNetics Operation, Mjärdevi Science Park, 58330 Linköping, Sweden
(TwinSpot Network is a subsidiary of EuroNetics Operation)

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From: Tomas Fasth <[email-masked]>
Date: Wed, 19 Nov 1997 17:15:04 +0100

Tim Showalter wrote:

> immutable so that once the delivery agent had written to the message
> store, it's never gonna change.

I don't regard this as a problem but a feature.
If you want to change the content of a message, including it's headers,
you have to make a copy, making your changes in that copy and store it
in the same place, probably also deleting the original message.
By being forced to do it this way, you are not breaking any cached
messages in MUAs running in disconnected mode (have those creatures
been invented yet by the way?).

-- 
Hälsningar/Regards

---

From: Tim Showalter <[email-masked]>
Date: Wed, 19 Nov 1997 13:56:25 -0500 (EST)

> been invented yet by the way?).

Ok; it was the only worry I had about modifying headers in the filtering
agent.  I withdraw it.