Thunderbird and Junk / Spam Messages

To deal with the large amount of unsolicited email ("spam" or "junk mail") that most people have to cope with, Thunderbird uses an adaptive filter that learns from your actions which messages are legitimate and which are junk.

Junk filter settings

Global junk preferences

Junk filtering is enabled by default. You can set global junk preferences to control what should happen to messages marked as junk. These settings will be used by all of your email accounts (although some settings can be overridden in the account settings, as shown below).

> Preferences > Privacy & Security > Junk


Per account settings

The junk settings in the account settings for each of your email accounts will override similar settings in the global junk preferences described above. In this section, you can also select address books which will be used as a whitelist. Any messages from senders whose email address is in a whitelisted address book will not be marked as junk by Thunderbird.

> Account Settings > Your Account > Junk Settings


Training the junk filter

Tell Thunderbird what is JUNK

In order for Thunderbird's junk filter to be effective, you must train it to recognize messages that you consider to be junk and messages that you consider to be not junk. So it is important to mark messages as junk before deleting them.

There are several ways of marking messages as junk.

  • You can click on the little icon in the "junk" column of the message list:
  • You can also click the Junk button on the message header toolbar:
  • Or you can press J on your keyboard to mark one or more selected messages as junk.
Thunderbird's junk filter has been designed to learn from the training data which you provide. Marking more messages as junk or not junk (see below) will improve the accuracy of your junk filter by adding more training data.

Tell Thunderbird what is NOT JUNK

Sometimes Thunderbird's junk filter might get it wrong and mark good messages as junk. Therefore, it is just as important to tell the filter which messages are not junk, especially on a new installation of Thunderbird.

Note: You should frequently (daily or weekly) check your Junk folder for good messages wrongly marked as junk by Thunderbird and mark them as not junk. This will recover the good messages and improve the correctness of the filter for the future.

There are several ways of marking messages as not junk.

  • Click on the Not junk button in the yellow junk notification below the message header:
  • Click on the orange junk icon in the junk column of the message list to toggle the junk status of a message:
  • Or press Shift+J on your keyboard to mark one or more messages as not junk.

Furthermore, you should regularly train the filter by marking a number of good messages as not junk - messages in your Inbox and messages that have been filtered into other folders. In this case, you can only use the keyboard shortcut Shift+J, because the Not Junk button appears only for messages that have already been marked as junk. Marking several messages per week will be sufficient. You can select several messages and mark all of them at the same time. Unfortunately nothing in the user interface indicates whether a message has already been marked as "not junk".

Other ways of blocking unwanted messages

Thunderbird's adaptive junk filter is not an absolute barrier against messages from a specific address or specific types of messages. You can have stronger mechanisms to stop unwanted messages.

Create filters manually

You can manually create your own filters. Consider:

Use an external filter service

You can also use an external filter service to help classify email and block junk.

  1. > Account Settings > Your Account > Junk Settings
  2. Enable the Trust junk mail headers set by option.
  3. Choose an external filter service in the drop-down menu.

Was this article helpful?

Please wait...

These fine people helped write this article:

Illustration of hands


Grow and share your expertise with others. Answer questions and improve our knowledge base.

Learn More