[Dovecot] Dovecot aspects of fighting spam

[Rainer Frey]

On Tuesday 01 June 2010 17:01:16 Phil Howard wrote:
> On Tue, Jun 1, 2010 at 10:45, Rainer Frey <rainer.frey at inxmail.de> wrote:
> > I guess you'll have the mental transfer of "fight spam" into "cause
> > dovecot to perform this and that action" yourself. The possible actions
> > are, in general, documented.
> 
> I cannot determine how deliver with an empty string give to -m would
> behave.  

This is just what I mean: the behavior of deliver -m has absolutely nothing to 
do with fighting spam. It is the same whether you want to use it for spam-
tagged mails or any other reason. Therefore you'll not find the description in 
thedovecot wiki bysearching for "fighting spam". You'll find it by searching 
for "deliver" (or LDA).

> OK, so a delivery-time sieve.

Yes, sieve is mostly (with dovecot: only) used at delivery time (Cyrus IMAP  
might have support for applying sieve scripts with IMAP, but if so, it is an 
exception).
> 
> > See http://wiki.dovecot.org/LDA/Sieve
> > If you use dovecot 1.2, using the new Dovecot Sieve plugin is highly
> > recommended above the  old CMUsieve.
> > See http://wiki.dovecot.org/LDA/Sieve/Dovecot
> 
> Ubuntu has me at Dovecot version 1.1.11.  

Then you need to read http://wiki.dovecot.org/LDA/Sieve/CMU
It is quite sufficient for your current needs - though I'd upgrade in the long 
run. CMUSieve (and ManageSieve) are already integrated in the package.

> Ubuntu has turned out to be
> difficult for managing upgrades when packages it has are instead
> compiled from source.  

This is not my experience. Esp. dovecot and postfix are easily managed from 
source. Installing the package 'build-essential' and then 'aptitude build-dep 
dovecot' should provide all you need to compile and install dovecot from 
source (which is documented in the wiki).
 
Also there is an unsupported archive with current dovecot packages, but AFAIK 
those are build from source releases instead of daily snapshot (and should 
thus be quite stable:

> I've had periodic high FPs with content detection in the past (on
> other mail servers I didn't control).  

This is why I recommended a combination of different measures. Content 
detection should come in last in that list, but still can be done at SMTP time 
(esp. with latest postfix and amavisd-new).

Rainer