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Using the Junk Mail Controls in Mozilla

This document is a supplementary tutorial on the Junk Mail Controls, which is not covered in Mozilla’s onscreen help.

This document is for your information only. It may help you take certain steps to protect the privacy and security of your personal information on the Internet. The information does not, however, address all online privacy and security issues, nor does it represent a recommendation by about what constitutes adequate privacy and security protection on the Internet.

  1. Using Junk Mail Controls
  2. Junk Mail Controls Options
  3. Junk Mail Controls and Filters
  4. Opting out of Junk mail
  5. Prevent your e-mail address from being harvested
  6. Is it safe to read spam mail?
  7. How do I bounce my message back to Junk mail senders?
  8. Web Resources

Using Junk Mail Controls

Mozilla’s Junk Mail Controls feature can evaluate your incoming messages and identify possible junk (or unsolicited) messages. The feature uses the Bayesian classification method, which requires that you first train Mozilla by showing it a bunch of mail that is junk, and a bunch of mail that is not. Then, you let it auto-classify new mail for you. If Mozilla makes any mistakes, you can correct them.

Do not be alarmed if the feature appears to do nothing when you first use it; the system will become very accurate if you use it often enough.

To use Junk Mail Controls:

  1. First, train Mozilla to recognize Junk messages and Non-Junk messages. There are three ways to toggle junk status of the selected message(s):

    • Open the Tools menu, and choose Mark Selected Messages or Mark Selected Messages as Not Junk.
    • Click on the Junk toolbar button.
    • Click to toggle the Junk Status column in the message list. (If you do not see it, click the right-most button () in the list header bar and select Junk Status from the pop-up menu.)

    When you toggle junk status, a trash-can icon will appear or disappear in the Junk status column to indicate the junk status of the selected message.

  2. Open the Tools menu and choose Junk Mail Controls.... Enable the feature for your mail account, and Mozilla will automatically classify incoming messages. (See Junk Mail Controls Options.)

  3. If you have trained it on virus mail, consider disabling the white listing (many mail viruses send bulk messages to people in the address book of the infected computer). Watch it catch messages that might contain a virus (e.g. Klez)

  4. Make sure to correct the Junk control when it incorrectly labels messages either as junk or not junk.

  5. To analyze existing messages, select messages, open the Tools menu and choose Run Junk Mail Controls.

Mozilla will only run the Junk Mail Controls when the training database has information on non-Junk messages. If the Junk Mail Controls does not work, select some messages and explicitly mark them as Not Junk.

Junk Mail Controls Options

To fine-tune how Junk Mail Controls works, open the Tools menu and choose Junk Mail Controls...:

  • Account: Choose an mail account to change the Junk Mail Controls settings for that account. (Note: all accounts share the same Junk training database.)

  • Junk Mail Log: Click the button to open a dialog showing you the history of Junk mail detections. You can disable Junk Mail Log from the dialog.

  • Enable Junk Mail Controls: Toggle this option to activate or deactivate junk mail classification.

  • Do not mark messages as junk mail if the sender is in my address book: Choose this option to prevent messages from people you know inadvertently classified as junk mail.

  • Move incoming messages determined to be junk mail to: Check this option to automatically move messages flagged as Junk to a special folder.

    • "Junk" folder on [account]: select this to use the default Junk folder.
    • Other: [account]: select this to choose your own custom-named junk folder.
    • Automatically delete junk messages older than __ days from this folder: If you are confident old messages classified as junk are indeed junk mail, check this option to automatically delete old junk messages after a grace period.
  • When I manually mark messages as Junk: Choose this to set what you want Mozilla to do when you manually mark messages as Junk.

    • Move them to the "Junk" folder: Choose this to move manually-marked Junk messages to the Junk folder.
    • Delete them: Choose this to move manually-marked Junk messages to the trash folder.

Junk Mail Controls and Filters

Junk Mail Controls runs after mail mail filters and applies only to the Inbox folder and its sub-folders. Use this to your advantage, for example, you can filter mail you are sure not to be Junk to a special folder outside of Inbox so that the messages will not be classified as Junk (especially useful if you subscribe to newsletters or if you are on a moderated mailing list).

Opting out of Junk Mail

Many spam messages include opt-out instructions. However, be warned that spammers lie and do not follow the opt-out instructions; your reply could merely confirm your e-mail address and invite more Junk mail.

Prevent your e-mail address from being harvested

Unfortunately, unless you keep your e-mail address private by giving it out only to friends, sooner or later spammers will harvest your e-mail addresses. Spammers usually harvest mail addresses by scanning mailing list and Usenet postings and Web sites. If you post to mailing lists, you can use one of many free mail providers to create a public account. If your public account get swamped by Junk mail, you can always create another one. If you post to newsgroups, you can use a public account or post anonymously, depending on the newsgroup rules.

Is it safe to read spam mail?

Mozilla will not automatically execute machine code in mail, and by default it does not allow mail to run script, so it is usually safe to open spam mail. (However, if you forward a message to another person, be courteous and scan any attachment for virus as what is safe to you may be unsafe for another.)

As far as privacy is concerned, there are a few things that you may want to know:

  • By default, Mozilla loads remote images in messages. You may not want this to happen because by sending a remote server a request to get an image you may confirm that you read the mail.

    To disable remote images in Mail & Newsgroups, open the Edit menu and choose Preferences. Choose category Privacy & Security, then choose the sub-category Images. Check the option Do not load remote images in Mail & Newsgroup messages.

  • If you do not wish to see any images, remote or stored in mail messages, or if you want to be able to turn on images quickly, open the View menu, choose Message Body As, and then choose Simple HTML or Plain Text. Also, open the View menu, and uncheck Display Attachments Inline.

    To turn on images for a specific message, choose the Original HTML option and check Display Attachments Inline.

  • By default, Mozilla will not allow mail messages to read or write cookies. To make sure this is indeed true, open the Edit menu, then choose Preferences. In the Preferences dialog, choose category Privacy & Security, choose sub-category Cookies, and then check if option Disable cookies in Mail & Newsgroup is checked.

    You can find more information on cookies on Netscape’s site.

  • By default, Mozilla does not run script in messages. To make sure this is indeed true, open the Edit menu, then choose Preferences. In the Preferences dialog, choose category Advanced, then choose sub-category Script & Plug-ins. In the Enable JavaScript for pane, make sure option Mail & Newsgroups is not checked.

How do I bounce my message back to Junk mail senders?

Many users have requested a bounce feature which would allow them to send a fake unknown-recipient return message back to senders of unsolicited mail. The aim is usually to punish Junk mail senders by costing them bandwidth to receive such bounce messages. Unfortunately, such measures usually punish innocent bystanders. Many junk mail senders fake others' e-mail addresses, and bounce would do double injury to these people. It may cost little for Junk mail senders to send and receive messages, but it costs network carriers to process both spam and your bounce messages, and your ISP may prohibit the uses of fake bounces.

Web Resources

If you want more information about spam and spammers, visit Also read the excellent Net Abuse FAQ. If you find these sites useful, be sure to bookmark them.