Most email clients contain some sort of SPAM prevention. On the Linux operating system you can employ such tools as Bogofilter or Spamassassin. Either of these tools are great for stopping SPAM – but what about using them with your favorite email client? With some Linux email clients you have to add extra applications in order to have one of these SPAM filters doing their job with your client. Some clients, however, have built-in tools to save you a little work. KMail belongs to the latter category. So long as you have either/or Bogofilter or Spamassassin installed, you are one step closer to having solid SPAM filtering.

In this article you will learn how to set up reliable SPAM filtering in the KMail mail client.

Bogofilter and Spamassassin

KMail can use either Bogofilter or Spammassassin easily. Read up on either tool and decide which application you want to use. I have had good luck with both, but I do believe Bogofilter is easier to set up. And since KMail will automatically detect either, the choice is yours.

You can install either tool from within the Add/Remove Software utility by following these steps:

1. Open Add/Remove Software utility.
2. Search for either “bogofilter” or “spamassassin” (No quotes).
3. Select either (or both) tools for installation.
4. Click Apply to install.

That’s it. Now you are ready to move on to KMail.

Kmail SPAM Wizard

Figure 1

When you have KMail set up and running click on the Tools menu and select the “Anti-SPAM Wizard” entry. When the Wizard opens the first thing it will do is detect which SPAM tools you have installed (see Figure 1).

Once the wizard has detected your SPAM tools, select the tool you want to use and click Next. For the purpose of this article I will select Bogofilter.

The next step in the wizard will ask you for two configurations:

• Mark detected SPAM as read: I prefer to unset this, because of the next configuration option.
• Which folder to relocate SPAM: By default KMail will move SPAM to the trash folder. I prefer to create a new SPAM folder in order to catch any false-positives.

By moving SPAM to a specific SPAM folder (and not the trash folder) and keeping SPAM unread, you are less likely to miss any email mistakenly marked as SPAM (false-positive).

The final window of the wizard gives you a report on what you have set up. In my case the wizard creates the following filters:

• Bogofilter Check
• Spam handling
• Classify as Spam
• Classify as NOT Spam

Click the Finish button and your KMail client is ready to learn. And learning is the key.

Help Bogofilter learn

Figure 2

Before Bogofilter can become a reliable SPAM filter, it has to learn what should be classified as SPAM and what should be classified as HAM. Here’s how I like to do it. Allow plenty of email to collect in your inbox. As the mail comes in take all SPAM (that is not already marked and moved) and move it to the SPAM folder. Once you have cleared your Inbox of all SPAM, select all mail in that folder and then click the Ham button (see Figure 2).

Now, once you have collect a good amount of SPAM in your SPAM folder open that folder up, select all the SPAM, and click the SPAM button.

You may have to do this trick a few times before Bogofilter has been properly trained. You will know when Bogofilter has become accurate with your SPAM/HAM.

Final thoughts

It couldn’t be much easier to catch and mark SPAM with KMail and Bogofilter. But if you find Bogofilter not as reliable as you would like, run the Wizard and try Spamassassin instead.

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With a little preparation this setup will go quickly. Without preparation, it will take some time for Bogofilter to learn SPAM/HAM.

Your preparation

The easiest way to train Bogofilter is to have a collection of SPAM and HAM ready (approximately 200 each for training purposes) for it to use in the training process. These will be placed in SPAM and HAM folders (respectively) to be used once Bogofilter is installed and ready. But before you get to that point, you need to install Bogofilter and the Bogofilter Evolution plugin.

To install the necessary items open up your Add/Remove Software tool. Within this tool do a search for “bogofilter” (no quotes). You should see two particular pieces of software to install: bogofilter and bogofilter-evolution. Mark both of these applications for installation and click Apply to install them.

After they are installed you are ready to set up Bogofilter.

Bogofilter setup

The first thing to do is to enable the Bogofilter plugin in Evolution. Click on the Edit menu and select the Plugins entry. In this new window that opens click the Bogofilter check box to enable to plugin and then close the window.

Figure 1

Now that the plugin is enabled, it’s time to configure it within Evolution. Go back to the Edit menu and select Preferences. When the Preferences window opens up click on the Mail Preferences button and then the Junk tab (see Figure 1).

From within the Junk tab the first thing to do is to select Bogofilter from the Default Junk Plugin dropdown. Now go back to the top and make sure “Check incoming messages for junk” is checked. Close this window after you have completed these steps.

Now you are ready to train Bogofilter.

Training

A lot of people complain that Bogofilter doesn’t work well. The main reason it doesn’t work well is because it hasn’t been trained. Remember those SPAM and HAM emails you collected in the SPAM and HAM folders? Now you are going to use them. First click on the HAM emails. These are all good emails (not SPAM). Select all of these and mark them as Junk. I know it sounds crazy, but it’s necessary. Now click on the Junk folder and you should see all of those emails you just marked as SPAM. Select them all again and mark them as Not Junk. Bogofilter just learned what you consider to not be junk.

Now click on the SPAM folder, select all of these messages, and mark them as Junk.

That’s it. Bogofilter should now be trained properly. And remember the more training you give Bogofilter, the smarter it will be.

Final thoughts

Bogofilter is a great tool for keeping SPAM out of your inbox. And best of all, it doesn’t require you to open up a terminal and issue a bunch of commands in order to get it working properly.

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