Re: [Gnu-arch-users] Re: the dangers of no reply-to munging; Xouvert update

[Andrew Suffield]

On Thu, Aug 21, 2003 at 06:17:50PM +1000, Robert Collins wrote:
> On Wed, 2003-08-20 at 17:36, Andrew Suffield wrote:
> 
> > > If you're on unix.... use formail - it will remove duplicates for you.
> > 
> > There's an exploit for that kicking around somewhere.
> 
> Got a reference? Some context maybe?

Can't find it offhand, but it's fairly simple anyway. Somebody can
selectively filter the mail you receive by sending you spam with
forged msgids. formail doesn't try very hard to make sure the messages
are really duplicates.

> > It also tends to remove the wrong duplicate.
> 
> How so? The messages aren't duplicates if they aren't identical.

The bodies are approximately[0] identical - the headers are
not[1]. Usually, one was sent to you, and one to the list. Most people
will filter these into different folders. Formail will pick one at
random (with a tendancy towards killing the list version, since that
usually takes longer to arrive - which is not at all what you wanted).

[0] List footers
[1] Resent-From, List-Id, etc.

-- 
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