From kmail-devel  Tue May 31 23:49:59 2005
From: Andreas Troschka <at.lists () om ! it ! eu ! org>
Date: Tue, 31 May 2005 23:49:59 +0000
To: kmail-devel
Subject: [Bug 106580] New: Disposition notification request process doesn't
Message-Id: <20050601014957.106580.at.lists () om ! it ! eu ! org>
X-MARC-Message: https://marc.info/?l=kmail-devel&m=111758340708638

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http://bugs.kde.org/show_bug.cgi?id=106580         
           Summary: Disposition notification request process doesn't work if
                    different in/outbound addresses
           Product: kmail
           Version: unspecified
          Platform: unspecified
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: kmail-devel kde org
        ReportedBy: at.lists om it eu org


Version:            (using KDE KDE 3.3.0)
Installed from:    Unlisted Binary Package
OS:                Linux

It is going to be a more and more spread use to have two different e-mail addresses (and accounts) one for the inbound (hidden by an alias address) and one for the outbound (not active for inbound, "unknown user").
This configuration stops SPAMmers to know your valid inbound addresses from getting them from the headers of your sent e-mails. It protects your privacy accordingly to the law of many countries.

But there is a problem with most MUAs (as with KMail) in handling such a setup due to the fact that the Disposition Notification process implementation is incomplete (see RFC2298).

Suppose:

two different addresses, one for inbound and one for outbound, each side

1. his.outb domain name------>[e-mail with DNR]------->your.inb yourdomain name
2. his.outb domain name<------[Ack of DNR]<------------your.outb yourdomain name

Actually when your MUA receives a DNR it takes the originating address and puts it into the To: field in the header of the aknowledgment e-mail it sends back to him.
This is obviously rejected by "his" outbound box. So he will never receive the requested confirmation (Ack). 

Solution
--------

The Ack has to be sent to the address specified in his Reply-to: field instead:

1. his.outb domain name------>[e-mail with DNR]------->your.inb yourdomain name
2. his.inb domain name<-------[Ack of DNR]<------------your.outb yourdomain name


and if no address is specified in this field than, and only than, the address specified in the return-path field has to be used (this should be the last resource!). 
Any reference at the From: field should be excluded due to the fact it often contains no or fake or outbound addresses!

Here the user operation sequence:

a)Open new mail composer
b)Write Destination address(es) in the fields To:, CC, BCC as needed 
c)Check "Disposition Notification Request"
d)Approve *proposed* Return-Receipt-To address (automatically taken from the address book for the destination address(es) specified)
d2)Otherwise select from listbox or edit directly
e)compose message text and send.

Andreas.
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