[Tickets #4664] Re: Display existing alternative rather than removed attachment

[bugs@bugs.horde.org]

DO NOT REPLY TO THIS MESSAGE. THIS EMAIL ADDRESS IS NOT MONITORED.

Ticket URL: http://bugs.horde.org/ticket/?id=4664
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 Ticket             | 4664
 Updated By         | Otto.Stolz at uni-konstanz.de
 Summary            | Display existing alternative rather than removed attachment
 Queue              | IMP
 Version            | HEAD
 Type               | Enhancement
 State              | Feedback
 Priority           | 1. Low
 Owners             | 
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Otto.Stolz at uni-konstanz.de (2006-11-16 06:49) wrote:

How could this situation be detected?

Imp 4.1.2 marks a removed part  thusly:
> ------=_NextPart_001_0001_319166C9.1979B12D
> Content-Type: text/plain;
> 	charset=UTF-8
> Content-Disposition: inline
> Content-Transfer-Encoding: 7bit
> 
> [Anhang entfernt: Ehemaliger Anhangstyp: text/html, Name: unbenannt]

This is tricky: The only safe criterion is the last line which depends on
the user's option settings. Note that this message may well be forwarded
to another user with different settings, or that the user may change hir
settings, after removing that part.

Another mailer (example seen today, but cannot be attributed to a
particular mailer) does it thusly:
> ------=_NextPart_000_001B_01C0CA81.7B015D10
> Content-ID: <121401Mfdab4$3f3dL780$75387018 at 57W81fa70Re>
> MIME-Version: 1.0
> Content-Type: text/plain; name="message.pif"; charset="iso-8859-1"
> Content-Description: Removed Attachment
> Content-Disposition: attachment; filename="Removed Attachment.txt"
> Content-Transfer-Encoding: quoted-printable
> 
> This attachment contained a virus and was stripped.
> 	Filename: message.pif
> 	Content-Type: audio/x-wav
> 	Virus(es): W32/Netsky-Q

Here, the key feature is the Content-Description line, in accordance with
RFC 2045, section 8: this can be set independently of the user's settings,
hence it can easily be detected.

So, my suggestion is:
- when removing an alternate part, set the Content-Description field, as
in the second example, above;
- when deciding which alternate part to display, parts marked in this way
should not be regarded as eligible,
- if possible, parts marked in the way of the 1st example, above, should
also be not eligible for display.