About the Anti-Spam Filter

Introduction

Plesk, our hosting control panel, has an antispam filter that benefits from training.

How to Train the Filter

1. Connect to the internet as normal, but do not start your e-mail program.
2. Log into your personal control panel at http://members.elirion.net:8443/ (Elirion dial-up and ISDN customers) or http://www.yourdomain.tld:8443/ (hosting customers) using your e-mail address and password.
3. Click on the Spam Filter button.
4. Click on the Training tab.
5. Scan through the list of e-mails in your inbox. These are marked with red and green icons to indicate that the filter thought the messages were spam or non-spam.
6. If any messages were incorrectly classified, check the checkbox next to them and click the Spam or Not Spam links above the list of messages to tell the filter how they should have been classified. You can reclassify several e-mails as either spam or non-spam at once.
7. If you are unsure whether a message is spam, click the subject of the message to preview it in a pop-up window.

Notes:

• Reclassifying a message only affects future messages. Plesk does not alter the spam filter flags on that message.
• You can get help on the spam filter by clicking on the Help button at the bottom of the left-hand menu in the control panel.

Setting Preferences

Once you are logged into your personal control panel, you can set preferences for the operation of the spam filter.

• Click on the Disable or Enable icon at the top of the preferences tab to turn the spam filter on or off.
• You can set the score at which Plesk considers e-mail to be spam. The filter is based on the widely-used SpamAssassin spam scoring system, which looks for patterns in e-mails and assigns a score indicating how likely it is that the message is spam. We suggest starting with a threshold of about 5 and adjusting it up or down as necessary after training the spam filter.
  • Using a threshold under 5 will increase the chances of "false positives", messages which are incorrectly marked as spam.
  • Using a threshold over 5 will increase the chanes of "false negatives", spam messages which are incorrectly marked as legitimate e-mails.
• You can set a subject line prefix, such as {SPAM}, that gets added to the beginning of the subject line for all e-mails that the spam filter thinks are spam. This is best used if you have an e-mail program such as Outlook Express which can only filter e-mail based on the subject line, or if you like having the subject line marked for probable spam e-mails. Most other e-mail programs can filter based on other "headers" that the spam filter puts in the message to indicate if the message is spam.
• You can have the filter delete spam when it comes to your mailbox. Since spam scoring is not always correct, we recommend that you do not use this option as it may result in legitimate e-mail being deleted unread.

Black and White Lists

Once you are logged into your personal control panel, you can click on the blacklist or whitelist tabs under the Spam Filter to enter e-mail addresses or domain names to black or white list.

• Blacklisted e-mails are always marked as spam. This is of little use with spam as spammers tend to use faked sender addresses, so you rarely get spam from the same e-mail address. It is best used for e-mail from people who you don't want to hear from and who won't stop sending you e-mail.
• Whitelisted e-mails are always marked as non-spam. This is best used for valuable e-mail that you don't want to ever be misclassified.

Using the Spam Headers

The Spam Filter adds "headers" to the e-mail message. These do not appear in your e-mail program unless you set it to show you headers. However, most e-mail programs will filter e-mail based on the headers.

If your e-mail program works with SpamAssassin by default, it will work with Plesk as Plesk inserts SpamAssassin-compatible headers in the e-mail.

If your e-mail program doesn't have a "SpamAssassin" setting, you can configure it to look for an "X-Spam-Status" header containing "YES".

Tips & Tricks

• Never press the "Clear Spam Filter Database" button. Retrain the spam filter instead.
• While the X-Spam-Status header shows whether the Spam Filter thought message was spam or non-spam, the X-Spam-Level header can be used for filtering e-mail in your mail program using a different threshold than in Plesk. For example, you could set Plesk to delete spam scoring 15 or more by setting the spam threshold to 15 and checking the "Delete spam mail when it comes to mailbox" checkbox. You can then route probable spam scoring less than 15 to a junk mailbox in your e-mail program after downloading it. For example, if you consider anything scoring above 5 to be probable spam, routing to a folder based on X-Spam-Level containing "*****" (5 asterisks) will work.

For More Information

If you have any questions about the migration, please contact us.