Set up the spam filter

To turn on the spam filter for a mailbox:

1. Go to Mail > email address > tab Spam filter.
2. Select the Enable spam detection for this email address check box.
3. Choose what to do with messages that are recognized as spam.
   • If you want to filter mail using the spam filter on your own computer, select the Mark spam option by adding the following text to the subject of e-mail, and specify how you want the spam filter to mark messages that are considered spam. The headers “X-Spam-Flag: YES” and “X-Spam-Status: Yes” are added to the source code of the message by default and, if you wish, the spam filter will also add a specific text to the beginning of the subject line and to the text of the message itself.
   • If you are sure that your spam filter is accurate, you can set the filter to automatically delete all incoming messages that are recognized as spam. To do this, select the Delete All Spam Messages option.
   • (Linux only) If you access your mailbox using the IMAP protocol and you want the spam filter to move all messages it considers spam to the folder named Spam, select the Move spam to the Spam folder option.

     Because all messages are automatically deleted from the Spam folder after thirty days, you should check the contents of this folder regularly to make sure you don’t miss any important messages. Move all non-spam messages to the Inbox.

     If the Move Spam to the Spam folder option is selected, you can train the spam filter and improve its accuracy by moving spam messages from the Spam folder to the Inbox and vice versa.

4. If the spam filter misses a lot of spam messages or incorrectly marks many messages as spam, you need to set the sensitivity of the filter. To do this, click Show advanced edits, and then enter the desired value in the Spam Filter Sensitivity field.

   The default value of 7 usually works fine, but if you have too much junk e-mail letting through, you can lower it by 1 and see if the number of spam messages allowed through decreases. If not, you can lower the sensitivity further. On the other hand, if the number of legitimate messages that are marked as spam increases, you can increase the sensitivity. In either case, it is recommended that you do not increase or decrease the sensitivity by more than one step at a time and that you wait a few days before changing the sensitivity further. Changing the sensitivity by more than one step at a time can lead to drastic changes in how the spam filter functions.

   Note: To further improve the accuracy of your spam filter, you can train your spam filter using the e-mail messages you receive, as described later in this section.

5. If you want to make sure you don’t miss any email from specific senders, add their email addresses or domain names to the Whitelist.

   Place each message on a separate line, or separate addresses with a comma, semicolon, or space. You can use an asterisk (*) as a replacement for a number of letters and a question mark (?) as a replacement for a single letter. For example: [email protected], [email protected], *@mijnbedrijf.nl. If you whitelist *@mijnbedrijf.nl, all email addresses under the domain name will be mijnbedrijf.nl whitelisted.

6. If you do not want to receive mail sent from specific domains or from individual senders, enter the email addresses or domain names in the Blacklist field.

   Place each message on a separate line, or separate addresses with a comma, colon, or space. You can use an asterisk (*) as a replacement for a number of letters and a question mark (?) as a replacement for a single letter. For example: [email protected], [email protected], *@spammers.net. Entering *@spammers.net blocks the entire domain spammers.net.

7. If you are using a Windows-based user account, you can also specify your familiar languages and character sets. E-mail messages written in the specified languages and character set will always pass the spam filter and will never be marked as spam.
8. For Windows-based user accounts, you can also specify IP addresses of computers or networks whose mail should always be accepted. When specifying network addresses, you specify the address, a slash, and the network mask. For example, 192.168.10.10/24.
9. Click OK.

You can improve spam detection accuracy if the SpamAssassin spam filter is enabled on the server and you can access your mailbox using the IMAP protocol.

To improve spam detection accuracy:

1. Access your mailbox using webmail or an e-mail program on your computer.
2. Check the messages in your Inbox. Move all spam messages to your Spam folder. This will allow the SpamAssassin spam filter to better recognize spam in the future.