Open source brings a spam-free lunch

David M Williams
Monday, 14 January 2008 07:22

Opinion and Analysis

Non-standard Internet Explorer extensions do nothing to help either; pages exploiting such are never going to be viewable as intended in other browsers because of the pervasive mantra within FOSS providers that standards be upheld and adhered to.

So, returning to our problem at hand, the standard for e-mail delivery is SMTP, the simple mail transfer protocol. All mail servers, no matter who the vendor, implement SMTP according to a defined and well-accepted standard known simply as “RFC 821”, which stood for almost twenty years before being updated in the form of RFC 2821.

Microsoft Exchange implements SMTP to receive mail. So does Lotus Domino. So does Sendmail. Consequently, a non-proprietary anti-spam solution can wedge itself between the Internet and your mail server, providing its own SMTP implementation and accepting mail in the first instance. It will cleanse the incoming mail of spam and then pass it on to your real mail server, giving a pure flow of clean e-mail. There’s a secondary advantage too; your e-mail server becomes one step removed from the public Internet.

Now, I have to be fair; this idea isn’t the sole domain of the open source world. Indeed, it’s the model used by services like MessageLabs who provide just this very service themselves. Your e-mail goes straight to them, they cleanse it and pass it on. It’s pure SMTP, with no regard for your operating system or mail server environment.

Yet, these services are businesses; they’re going to charge for what they do. That’s fair enough, but it can easily become depressing when your users say “We have too much spam; you must do something” but the solutions are all like taxi meters, ticking over – “you have how many mailboxes?” they ask. “How many domains do you have?”, “How many e-mail messages do you receive a day?” Every question adds up; every single item adds up.

Can open source compete? Pleasantly, the answer is definitely yes – with some impressively mature and stable products available right now. It doesn’t matter if you’re a Windows or Linux user, it doesn’t matter which mail environment you run.

SpamAssassin
SpamAssassin is a widely-deployed product, which in fact serves as the engine underlying a number of commercial products. It is a mature system and employs a rich suite of tests to identify genuine spam. This includes analysing the message text, the headers of the e-mail, statistical models, DNS blacklists and collaborative filtering databases.

SpamAssassin is well supported and provides a wide range of questions and answers on its web site; at the FAQ you’ll find tips on improving system performance, information on how the product actually works and determines messages are spam, how to contribute, and many more.

All this said, SpamAssassin is powerful but complex; it requires some effort be put in to make it work on any specific system. Ironically, this has lead to the rise of commercial anti-spam products based on the free open-source SpamAssassin engine, with the proprietary product merely providing a nice GUI and some tie-in with specific mail servers.

So, let’s go a step further and find an all-in-one FOSS solution.

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