[Dovecot] what best for anti-spam filter?

[Arnaud Abélard]

On 07/24/2012 10:49 AM, Morten Stevens wrote:
> On 24.07.2012 09:16, Arnaud Abélard wrote:
>
>> And first of all, even if this is not dovecot related, use a
>> greylisting solution.
>
> No, greylisting is really a bad solution. It is not RFC compliant and
> delays the mail traffic.
>
> I would prefer a pre-queue content-filtering solution like MIMEDefang or
> amavisd-new.
>
> Best regards,
>
> Morten

As far as I know greylisting is RFC compliant it even has its own RFC:
http://tools.ietf.org/html/rfc6647

Greylisting was prefered for a simple reason If a mail is accepted on 
our servers we have to deliver it to the user (unless it has a virus)

- With greylisting we aren't rejecting potentially spammy mails, we are 
rejecting misbehaving servers. That's important, legally speaking. We 
could be in trouble if we rejected an important mail by mistake when our 
server actually accepted it.

- Our users already complain they are getting too much spams (we mark 
them with [SPAM] in the subject). Without greylist and for the reason I 
stated above, even if we were able to detect the bot spam as spams, we 
wouldn't want to reject it and our users would be flooded.

Greylisting isn't a perfect solution. Just a good one. Depends on what 
you want, I guess.

Arnaud


-- 
Arnaud Abélard (jabber: arnaud.abelard at univ-nantes.fr)
Administrateur Système - Responsable Services Web
Direction des Systèmes d'Informations
Université de Nantes
-
ne pas utiliser: trapemail at univ-nantes.fr