Re: [exim] reject html letters and gif attachments!

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Szerző: Exim users mailing list
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Címzett: Vladimir Koshelenko
CC: exim-users
Tárgy: Re: [exim] reject html letters and gif attachments!
On Tue, Mar 13, 2007 at 02:27:29PM +0300, Vladimir Koshelenko wrote:
> Здравствуйте.
>
> В сообщении от 13 марта 2007 unaos написал(a):
> > good morning my dear brothers of spam fighting corps.! :D
> > now my problem is going panic state - flooded over with spam so making
> > some cardinal decisions.
> > and at first - plain text letters only, what will you say. is your
> > experience showed good results or it's not worth because of users feel
> > ungood ?
> > and filter image attachemetns the second.
> >
> > i'm using exim 4.62 on gentoo with exiscan and exiscan-acl flags enabled.
> >
> > how can be that possible and released ?
>
> Filtering HTML seems as bad idea. Indeed you can - if you want to loose half
> of mail from outside.

Sorry for little offtopic. Filtering HTML messages may be a part of corporative
security policy. And it's possible to give 550 error with text like
'Only plaintext messages is acceptable' ;)

> Filtefing image attachments is easy. If your Exim built with 'demime' check,
> just add on top of DATA ACL this:
>
>   deny
>       message     = Images not allowed, please zip them before send.
>       demime      = gif:jpg

>
> It helps as emmergency. If you want some advansed spam filtering - read Exim
> manual and this document http://tldp.org/HOWTO/Spam-Filtering-for-MX/


'demime' is deprecated way to implement filtering attachments
(http://www.exim.org/exim-html-4.66/doc/html/spec_html/ch41.html#SECTdemimecond)
It's recommended to use SMTP MIME ACL instead.

Keep in mind that since exim does not support RFC 2231 yet, neither MIME ACL
nor 'demime' are not filtering efficiently attachments with non-ASCII file names.

-- 
Kind Regards,    Alexander Shikoff
minotaur@???
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