Mozilla's spam filter

Mozilla has a built-in Baynesian Spam filter. In order to use it, you have to tag email messages as spam in order to Mozilla to "learn" what it should consider spam. Mozilla has a routine that examines messages that are marked as spam and creates a database of characteristics for those messages. In the future, when Mozilla encounters a new message that meets the characteristics of other spam messages, it will automatically tag that message as spam and move it into a mail folder called Junk (by default).

Turning on the Mozilla Junk Filter

Mozilla's Junk filtering system is turned on by default on CLAS administered computers. At home, you may need to turn it on though. Here's how to do it:

- Open the Mail client

- go to the Tools menu and choose "Junk Mail Controls".

- Here is a sample screen showing the default CLAS configuration:

Teaching Mozilla what messages are Spam

There are three ways to tag messages as Spam (or Junk):

- Highlight the message using your mouse, then click on the Junk button in the toolbar.


- Right click on a message and select Mark, then As Junk from the menu.


- Click in the Junk mail column in the message listing to put a "junk" icon next to the message. The Junk mail column has a picture of a recycling bin at the top.



In my experience, you have to tag about 3 messages of the same type as Junk before Mozilla will automatically recognize future versions of it.  As you continue to tag more and more messages as spam, Mozilla will get better at recognizing it. However, it is a never-ending process - spammers are constantly trying to come up with new methods to try to get around such filters.

Note that while Mozilla's spam filter is very good, but it certainly isn't perfect, and on occasion, a legitimate message can be tagged as Junk by the filter. This is the reason for using the Junk Mail folder. It should be examined periodically to make sure that there aren't any mis-tagged messages in it, rather than telling Mozilla to delete them out right.

If you do find a message that shouldn't be tagged as spam, either uncheck the Recycling Bin icon next to it, right click and choose Mark as Not Junk, or click on the "Not Junk" icon in the toolbar to teach Mozilla that this type of message should not be tagged as Junk in the future. You should then move the message out of the Junk folder into your In box (or other mail folder) where it belongs.

back to top