• In the Junk Mail Controls window, you should fill out the fields exactly as shown below except with your personal information. Check the box under White Lists to instruct your filter to ignore senders from your address book since these should be guaranteed safe.
• You will want to store the filtered messages in a Junk Mail Folder rather than deleting them automatically, just in case a legitimate message is incorrectly filtered out. Thunderbird will automatically create the folder, which you should check periodically for any important messages that may have slipped in.
• You may automatically delete junk messages after any specified period, but you should be sure to check for real messages before you purge them, thus set the auto-delete period according to how often you can check your junk mail folder.

Junk Mail Filtering Under User Account in Thunderbird

Click on the Adaptive Filter tab and Enable the adaptive junk mail detection. This will allow you to mark messages in your inbox that were not picked up by the filter as junk, and eventually train the filter to recognize them. You can also train the filter to recognize legitimate files that were accidentally placed in the junk mail folder as messages for you inbox by unmarking them in your junk mail folder.

Configuring your Spam Level Detection

Since there is no real way for email servers to define which messages are considered to be Spam to which users, it must scan incoming mail for certain attributes, and then give each message a "score" based on these attributes. With Thunderbird, you can designate a minimum level of Spam likelihood for a message to be filtered into your Junk Folder.

1. Go to Tools -> Message Filters...

   

2. Click New...
3. In the Filter Rules window, name your filter. In our exampled we will name it Spam.
4. In the next section, "For incoming messages that" select "Match all of the following".
5. Click on the first scroll-down menu and choose Customize...
6. Call your new message header "X-Spam-Level" and click Add followed by OK. You can now select X-Spam-Level from the first scroll-down menu.
7. In the next scroll-down menu choose "contains".
8. In the third field type in 5-10 X's, each X indicating that a message contains 10% of the Spam attributes. For example, XX would mean that you would like to filter out all messages that have at least a 20% likelihood of being spam-mail, XXX is 30%, etc. We advise you to designate it to at least 8 (XXXXXXXX) or 80% likelihood of being Spam, otherwise the filter may label wanted messages as junk mail. If at 80% you find you too many wanted messages are ending up in the spam folder, you may adjust the setting and add another X to make it 90% likely to be spam before being moved to the spam folder. Conversely, if you find you are receiving too many spam messages in your inbox at 80% and you are not losing wanted messages in the spam folder, you may adjust the setting lower, by removing an X, to say 70% likelihood of being spam.

   

9. The last step is to check the box next to "Move to folder" and then select the folder into which you would like to store the filtered out mail. We suggest storing it in a junk mail folder rather than moving them directly to trash so that you will be able to check it for wanted messages periodically. See the instructions at the top of this page to customize your junk mail folder.
10. Click OK to return to the Message Filters window, where you can run a junk mail scan on the messages currently in your inbox by clicking Run Now.

You can always check the Spam Level of any message by viewing its headers. In the main menu select View -> Headers -> All and click on the message you would like to view. You should see the X-Spam-Level and its "score" in X's for that message.