Good & free Exchange spam filter

Question

Do you know a good (and free, if possible) Microsoft Exchange 2003 spam filter?

Solution 1

If you don't mind an outsourced service, you may be able to use Safentrix as a gated filtering solution. They claim free service that scales up to 20,000 users. I have not tried this service, so your mileage my vary.

There are a slew of other paid gating services that you can use to filter your incoming mail such as MX Logic (have heard good things about them).

If you want an in-house solution, you could look at a hardware device such as a Barracuda, or a software solutions such as ModusGate.

Solution 2

We find that properly configured DNS/Realtime Black List (DNSBL/RBL) works wonders, part of the Intelligent Message Filter in Exchange 2003. We use:

• SpamHaus SBL+XBL+PBL: http://www.spamhaus.org/
• SORBS Dynamic IP Address Block List: http://www.sorbs.net/

See this article for how to configure it in Exchange 2003.

Solution 3

There's an article which provides a overview of some solutions to that issue.

Solution 4

I've had a lot of trouble with GFI and spam assassin. Both are good products but lack any decent detection rates. And depending on your setup (especially with multiple servers) you'll run into a lot of config problems. (Though GFI support is really on the ball - I was able to report bugs and get a workaround and then working fix within a week.)

What I ended up doing was going with the now google owned Postini and I haven't looked back. It "just works" (you set your MX records to them and reject email not from their servers in your firewall) and is very powerful and you can get it as low as $1.50 a mailbox.

You get a quarantine email at the end of the day with a list of subjects it picked up and you can just click deliver next the email you want. It also filters out "blatant spam" that doesn't even hit your quarantine. My company used to get sever hundred spam messages a day per mail box (about 40 boxes) and where GFI would catch about %75 of them, postini catches much closer to %99.

Dealing with spam used to take up a lot of my time, now Its rare when I get complaints about it in a week.

Solution 5

I don't know of many free products, although i have seen an implementation of spam assassin for exchange 2003. Most products are paid for ones, some to of the popular ones being:

• GFI Mail Essentials
• XWall Spam Filter
• Sunbelt Ninja Email Security

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Comments

[Sam Cogan]

Exchange 2003 or 2007?

[Olivier Payen]

Sorry, Exchange 2003

[Justin Scott]

I'm curious if you tried Safentrix, and if so, how that worked out for you.

[Christopher Edwards]

Well, safentrix is defintely going on my eval list!

[MarkR]

Blocking mail completely due to the sender IP appearing on a blacklist is a very bad idea; you will definitely block some legitimate senders.

[Duncan Smart]

Aren't false positives a risk with any anti-spam system?

[Atulmaharaj]

False positives are always a risk, but most blacklists have a reputation of being risky. The ones you mention are better than average, but for example I wouldn't outright block dynamic IP's. A layered approach is much safer and can more easily adapt to changing patterns.

[Atulmaharaj]

Good article, but all mentioned products are commercial.

[Atulmaharaj]

What did you do with the spam? How did you let the recipients retrieve false-positives or mark spam?

[Fergus]

This is an excellent product.

[Doug S]

What do you use now that Postini no longer exists?