How do I filter spam locally in my email client?

There are two important levels to blocking spam:

1. Local level - This article discusses how to filter spam using your email client.
2. Server level - We have a separate Answers article discussing ways to stop spam at the server level.

It is important to implement both levels of filtering to control the amount of spam you receive.

This article explains how to use your email client's (Eudora, Thunderbird, etc...) built-in spam filtering. Filtering locally allows you to customize the spam filter based on what you want to be classified as spam. The more email you mark as spam and not spam, the better your email client will get at identifying spam messages in the future. Filtering spam locally does not replace the filtering done at the server level. Instead, it provides another layer of protection against spam.

• Thunderbird
• Eudora
• Apple Mail
• Webmail
• Mutt

Thunderbird

Thunderbird's junk mail filtering system requires training to improve accuracy. Because of this, we recommend that you don't initially have junk mail sent to a separate folder. By keeping it in your inbox, you can teach Thunderbird what is spam and what isn't. Once you are satisfied with Thunderbird's success rate, you can have spam automatically moved to a "junk" folder.

Set up junk mail identification

1. Click Tools | Junk Mail Controls...
2. In the "Settings" tab use these settings (where "brubaker@seas.upenn.edu" is your email address):
   
3. In the "Adaptive Filter" tab, make sure "Enable adaptive junk mail detection" is checked.
   
4. Click OK at the bottom of the window.

Training the junk mail filter

To train the junk-mail filtering, you need to mark messages that you've received as either "junk" or "not junk". There are various ways that you can mark messages:

• Right-click on a message and choose Mark -> As Junk (or As Not Junk).
• Select a message and from the "Message" menu, choose Mark -> As Junk (or As Not Junk).
• Select a message and click on the Junk icon on the toolbar.
• Select a message and type "J" (for Junk) or "Shift+J" (for not Junk).

Initially, the automatic junk mail detection for incoming messages might not be very accurate because it needs to be trained.

Stop here if you want to spend some time training Thunderbird's spam filter. Start from this spot once you are satisfied Thunderbird knows what is spam and what isn't.

Create the Junk mail folder

Note: This step will create a new "folder" for your junk mail. Be aware that this is distinct from your "spamfolder" used by the SEAS SpamAssasin filter. Combining these two folders is not recommended since they are used by two separate filtering systems.

1. Check Tools | Account Settings -> Server Settings -> Advanced... Make sure IMAP Server Directory is "~/Mail/", and make sure "Show only subscribed folders" and "Server supports folders that contain sub-folders and messages" are both UNchecked.
2. Make sure you don't already have a folder called "Junk". If you do, you can skip the next step.
3. Click File | New | Folder... Type the name as "Junk". Leave the "Messages Only" radio button selected.

Set up junk mail to automatically move to Junk folder

Warning: If you do this step before a month or two of training (as described above), you may find many real messages get sent to the Junk folder.

1. Click Tools | Junk Mail Controls...
2. In the "Settings" tab use these settings (where "brubaker@seas.upenn.edu" is your email address):
   
3. Click OK at the bottom of the window.

It is advisable to check your Junk folder every few days to make sure no good mail has been placed there. Also, spammers will continue to evolve new ways of getting around spam filters, so there will always be a few messages that get through the filter. Identifying a spam message that gets through as spam will help the filter recognize similar messages as spam next time.

Note: using the settings suggested above, messages in your Junk folder older than 30 days will be deleted.

Eudora for Windows (version 6+ required)

Eudora's junk mail filtering system requires training to improve accuracy. Because of this, we recommend that you don't initially have junk mail sent to a separate folder. By keeping it in your inbox, you can teach Eudora what is spam and what isn't. Once you are satisfied with Eudora's success rate, you can have spam automatically moved to a "junk" folder.

Set up junk mail identification

1. Click Tools | Options...
2. Scroll down to the "Junk Mail" icon and use these settings:
   
3. Click OK at the bottom of the window.

Training the junk mail filter

To train the junk-mail filtering, mark a message using "junk" and "not junk". If you have a message that is Junk, highlight the message, then use the Junk command. The message will be given a Junk score of 100. If you have a message identified as junk that is not Junk, highlight the message, then use the Not Junk command. The message will be given a Junk score of 0. There are various ways that you can mark messages:

• Right-click on a message and choose Junk (or Not Junk).
• Select a message and from the "Message" menu, choose Junk (or Not Junk).
• Select a message and type "Ctrl+J" (for Junk) or "Ctrl+Shift+J" (for not Junk).

Initially, the automatic junk mail detection for incoming messages might not be very accurate because it hasn't yet been trained very much.

Stop here if you want to spend some time training Eudora's spam filter. Start from this spot once you are satisfied Eudora knows what is spam and what isn't.

Create the Junk mailbox

Note: This step will create a new "mailbox" (or "folder") for your junk mail. Be aware that this is distinct from your "spamfolder" used by the SEAS SpamAssasin filter. Combining these two folders is not recommended since they are used by two separate filtering systems.

1. Check to see if you already have a mailbox called "Junk" listed under "<Dominant>". If you already have one, you can skip to the next section.
2. To create the mailbox, click Mailbox > Dominant > New... Type the name as "Junk". Leave the "Make it a folder" check box UNchecked (which is the default).

Set up junk mail to automatically move to Junk folder

Warning: If you do this step before a month or two of training (as described above), you may find many real messages get sent to the Junk folder.

1. Click Tools | Options...
2. Scroll down to the "Junk Mail" icon and use these settings:
   
3. Click OK at the bottom of the window.

It is advisable to check your Junk folder every few days to make sure no good mail has been placed there. Also, spammers will continue to evolve new ways of getting around spam filters, so there will always be a few messages that get through the filter. Identifying a spam message that gets through as spam will help the filter recognize similar messages as spam next time.

Note: using the settings suggested above, messages in your Junk folder older than 30 days will be deleted.

Apple Mail

Apple Mail's junk mail filtering system requires training to improve accuracy. Because of this, we recommend that you don't initially have junk mail sent to a separate folder. By keeping it in your inbox, you can teach Apple Mail what is spam and what isn't. Once you are satisfied with Apple Mail's success rate, you can have spam automatically moved to a "Junk" folder.

Set up junk mail identification

1. Click Mail | Preferences
2. Click the Junk Mail icon and use these settings:
   
3. Close the Junk Mail window.

Training the Junk mail filter

Initially, you will need to train the spam filter to recognize the messages you consider to be spam. If a valid message is incorrectly marked as junk, highlight the message, go to the Message menu, then Mark, then As Not Junk Mail.

If a spam message is not marked as junk, follow the same steps as above, but select Mark -> As Junk Mail. There is also a Mark as Junk/as Not Junk icon in the Mail's toolbar which you can use instead of the menus.

Over time, Mail will become more and more accurate at correctly identifying spam. Spammers will continue to evolve new ways of getting around spam filters, so there will always be a few messages that get through. Identifying a spam message that gets through as spam will help the filter recognize similar messages as spam next time.

Stop here if you want to spend some time training Apple Mail's spam filter. Start from this spot once you are satisfied Apple Mail knows what is spam and what isn't.

Creating a new folder

Note: This step will create a new "folder" for your junk mail. Be aware that this is distinct from your "spamfolder" used by the SEAS SpamAssasin filter. Combining these two folders is not recommended since they are used by two separate filtering systems.

1. Check Mail | Preferences... -> Advanced Tab. Make sure the IMAP Path Prefix is "~/Mail/".
2. Make sure you don't already have a folder called "Junk". If you do, you can skip the next step.
3. To create the new folder, click Mailbox -> New Mailbox... Type the name "Junk".

Set up junk mail to automatically move to Junk folder

Warning: If you do this step before a month or two of training (as described above), you may find many real messages get sent to the Junk folder.

1. Click Mail | Preferences
2. Click the Junk Mail icon and use these settings:
   
3. Close the Junk Mail window.

It is advisable to check your Junk folder every few days to make sure no good mail has been placed there. Also, spammers will continue to evolve new ways of getting around spam filters, so there will always be a few messages that get through the filter. Identifying a spam message that gets through as spam will help the filter recognize similar messages as spam next time.

Webmail

Turn on spam filtering for your account

Webmail's spam filtering tools require that your personal spam filter be turned on for your account. To activate spam filtering on your account, follow these steps:

1. Visit your SEAS Account Management page.
2. Login using your SEAS user name and password.
3. On the left, click on Spam Blocker and Blocked Addresses.
4. Click on the Enabled radio button beneath Spam Block.
5. Click on Update Email Filters further down the page to save and exit.

This will enable the default spam filter settings, see more settings for further customization.

Training the filter

You can now use the Report as Spam and Report as Innocent links in Webmail:

"Report as Spam" will take any selected message(s), add its characteristics to your personal spam filter, and delete the message.

"Report as Innocent" will take any selected message(s) and remove its characteristics from your personal spam filter. This link is generally used in your "spamfolder" to tell the filter that it misclassified a valid email.

Managing your spamfolder

Once you have started training your filter, it will begin to move new messages it thinks are spam to your "spamfolder". It is advisable to check your spamfolder every few days to make sure no good mail has been placed there. If you find a valid email in your spamfolder, simply select the message and click the Report as Innocent link.

Mutt

Turn on spam filtering for your account

Mutt's spam filtering tools require that your personal spam filter be turned on for your account. To activate spam filtering on your account, follow these steps:

1. Visit your SEAS Account Management page.
2. Login using your SEAS user name and password.
3. On the left, click on "Spam Blocker and Blocked Addresses".
4. Click on the "Enabled" radio button beneath "Spam Block".
5. Click on "Update Email Filters" further down the page to save and exit.

This will enable the default spam filter settings, see more settings for further customization.

Training the filter

You can now use *s (that's asterisk-ess) to add the characteristics of a message to your personal spam filter. *h (asterisk-aitch) will remove the characteristics of a message from your personal spam filter.

Managing your spamfolder

Once you have started training your filter, it will begin to move new messages it thinks are spam to your "spamfolder". It is advisable to check your spamfolder every few days to make sure no good mail has been placed there. If you find a valid email in your spamfolder, simply use *h to report the message as not spam.