Re: [Exim] Attachments and bounce messages

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Author: Chris Edwards
Date:  
To: 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.

|
| 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.

|
| 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?


One of the nice things about Exim is that it returns a decent chunk of the
messaage body. That way, when a bounce message gets bounced, its possible
to see the headers of the *original email* - often a great benefit for
troubleshooting.

Setting bounce_return_body FALSE would break this (very useful) ability.

I vote not to create such a feature, or, if it must be created, then make
the default TRUE (existing behaviour).

This seems like the slippery slope to the useless bounce messages that
come out of exchange and other pieces of commercial junk.


| 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.


Its a hack, but quite a good one :)


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


Again, a hack, but quite a good one :)




--
Chris Edwards, Glasgow University Computing Service