Date: Wed, 06 Jun 2007 19:14:39 +0200 From: Gabor Kovesdan <gabor@FreeBSD.org> To: Richard Coleman <rcoleman@criticalmagic.com> Cc: freebsd-questions@freebsd.org Subject: Re: Seeking recommendation for anti-spam software Message-ID: <4666EB7F.2060807@FreeBSD.org> In-Reply-To: <4666DA3B.3070609@criticalmagic.com> References: <4666DA3B.3070609@criticalmagic.com>
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Richard Coleman escribió: > I am running a mail server using Postfix and Dovecot. I would like to > hear people's recommendation for which port to use to add server side > anti-spam. The problem these days is a richness of choices, so it's > hard to know port which to try. > > And call it a quirk of mine, but I really dislike (server) software > with a large number of dependencies. That rules out Spam Assassin. > But I am fairly conversant with mail and Postfix/Dovecot in general, > so I don't mind any integration work. > > I apologize if this has been discussed before, but I just joined the > list (I am already on so many FreeBSD lists already). I appreciate > any insight that people can offer. > Hello Richard, I think the most common (and thus more mature) solution for this are amavisd-new + SpamAssassin + clamav, they have a lot of dependencies, though. Clamav catches all the viruses, just the spams had caused problems with this configuration, before I started to use postgrey. I see your concerns about dependencies, but I think sometimes we have to make sacrifices for the most appropriate choice. This also applies to the next solution I recommend you and this is greylisting with postgrey. It does not have too much dependency, but it works in a way, that you can loose important mails as well. The concept of greylisting is that the server responds to the sender with an error code meaning a temporary failure and places the sender to a list called greylist when a mail is being sent. After some minutes (5 or so), well-configured STMP servers resend the mail, when your server notices, that the given server was greylisted, and now it can be trusted. Spam bots don't usually resend mails, they are too primitive for this atm. It can change in the future, but for now, the method works, it's been very well for me. The only problem is that there are STMP server that are configured in a weird way and they don't send out mails later again. Postgrey offers a solution, though. You can place such servers to a whitelist and they will be excluded from the greylisting. I have heard good experiences about dspam as well, but haven't used it, thus I can't form any opinion. Regards, -- Gabor Kovesdan FreeBSD Volunteer EMAIL: gabor@FreeBSD.org .:|:. gabor@kovesdan.org WEB: http://people.FreeBSD.org/~gabor .:|:. http://kovesdan.org
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