Question about Sieve and "filters"

Cyrus Daboo daboo at
Wed Jul 9 12:08:59 EDT 2003

Hi Michael,

--On Tuesday, July 8, 2003 9:38 PM -0700 Michael Fair 
<michael at> wrote:

| What do others think about this?
| Would this simple "pass through" filtering be useful?
| I'm primarily thinking of Spam catchers, Virus Scanners,
| and any other use where shoving the email through an
| external application would be useful.

First off there is a general reluctance, from a security standpoint, of 
allowing sieve to call out to arbitrary bits of code. I suspect that would 
frighten most sysadmins if users were allowed to write their own bits of 
code to run via sieve.

The alternative is to build specific extensions in sieve to accomplish 
particular tasks. In particular I have written a 'spamtest' and 'virustest' 
draft (link below) that proposes adding two new tests that return a fixed 
numeric range of values that can be tested against. Its up to each sieve 
implementation to choose how the results themselves are actually determined 
- I would envisage a plugin architecture that allows different spam/virus 
check systems to be used, but the user does not get to choose which - that 
would be a compile/configuration option for the server admin. The main goal 
for these extensions was to actually remove the need for end-users to know 
about the particular spam/virus test system in use, which would otherwise 
require them to tailor scripts specifically for those systems. The new 
tests allow scripts that do spam/virus checking to be portable across 
different systems, and to also allow sysadmins to change spam/virus 
checkers without having to have users change all their scripts. Given that 
spam checking tools are changing so rapidly right now, this solution would 
be really useful.


Cyrus Daboo

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