Re: [Exim] Attachments and bounce messages

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Author: Wakko Warner
Date:  
To: Philip Hazel
CC: exim-users
Subject: Re: [Exim] Attachments and bounce messages
> The latest spate of viruses has caused someone to ask me if attachements
> should be removed from messages that are returned with bounces.


Attachements yes, but not text/plain ones.

> The problem is that Exim doesn't analyse message bodies in any way.
> Properly sorting out MIME parts isn't trivial, as I understand it.


I've done MIME parsing in perl. It was fun. I did that so I could save
each part of a message as a seperate file (Don't ask =)

> Three fairly simple things could be done:
>
> 1. An option called bounce_return_body, defaulting TRUE, which, if
>    turned off, would cause only the header to be returned in a bounce.
>    I suspect few would set it. Should the default be FALSE?


Definately not in favor of this.

> 2. An option called bounce_something which would do a simple job of
>    looking for a "boundary" in a Content-type: header, and just return
>    up to the second boundary - i.e. return only the first part of a
>    message, assuming that it is not an attachment. I'm not all that keen
>    on this one, because it is a hack.


What if the message is a multipart alternative with attachments. You'll
have to look at the boundaries for the nested part.

I just looked at a message I have. It's type is multipart/mixed. First
part under it is multipart/related. First part under that is
multipart/alternative (it was outlook that sent it to me BTW), then finally,
it's text/plain.

IMO, the text/plain should be the *ONLY* part sent and *ONLY* upto the first
"begin xxx somefile" line (where xxx is 3 octal digits) or the size limit
whichever comes first.

Writing the mime parser I played with different aspects of a message
including UUencoded files inside of plain text messages with different MUAs

> 3. The default value of return_size_limit is 100K. It could be reduced
>    to, say 10K.


I would be infavor of that since I've been bombarded myself with 100kb
bounces and my server is on dialup.

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