Anti-Spam

Do you hate spam? I do. I get hundreds of spam a day! I’ve tried several methods to stop spam. Outlook rules, procmail regex filters, black/white lists and others. But all of them are not clever enough. After tried SpamBayes, I believe the filters can kill spam.

I’ve installed a spam filter plug-in (SpamBayes) for my Outlook 2002. I just gave 10 spam emails and 10 non-spam emails to the filter. After the training the filter works very well. And I was able to disable the stupid Outlook’s rules.

But it still have a problem. I have to receive all mails and filter them locally. It should be better to recognize the spams at the server-side. So I decided to setup a server-side filter. Fortunately, SpamBayes works well with procmail.

Our email system is powered by the last stable postfix. I am very care about secure issue, so SMTPs, POP3s, IMAPs and HTTPs have been configuated for sending, receiving and reading email. To enable the SpamBayes filter, I just add a few rules to the procmailrc file. Now, all coming emails will be handled by SpamBayes first and delivered to different folders. Spam will be delivered to “Spam Certain” folder, unsure will be delivered to “Spam Unsure” folder and ham will be leave in the Inbox.

SpamBayes’ accuracy is dependent upon having a “sufficient” sample from which to make its decisions. I have to teach SpamBayes which is spam and which is not. There’re two special folders named ‘Filter Train/Ham’ and ‘Filter Train/Spam’ in my mailbox. I wrote a small script to let SpamBayes train from the two folders and empty them after a successful training. Copy the wrong delivered emails and unsure emails to the Ham and/or Spam folders. SpamBayes will train and handle them correctly next time.

Everyone has a different idea of what is spam. So we have individual spam databases for each user.

Now, guys use our email system are able to receive non-spam emails to local mailbox using POP3s and train the filter using IMAPs or the webmail. It saves the time, bandwidth and money.

Next, I am trying to find a better anti-spam solution for large scale. For instance, OnlineNIC Inc. the company I am working for currently. It hosts thousands of virtual hosts, email boxes. The solution should be clever, effective, customizable. And it should be able to filter both incoming and outgoing emails.

Resources,
SpamBayes
Will Filters Kill Spam?
OnlineNIC Inc.