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#### Setting Up SpamAssassin Spam Filter

To switch on SpamAssassin spam filter:

1. Click Server shortcut in the navigation pane.
2. Click Mail in the Services group.
3. Select Spam Filtering tab.
4. To allow server wide filtering based on the settings you define, select the Use server-wide settings check box.
5. To let your users set their own spam filtering preferences on a per-mailbox basis, select the Allow personal settings check box.

   Now all the incoming mail will be filtered on the server side. By default, spam filter does not delete spam mail, it only adds the "X-Spam-Flag: YES" and "X-Spam-Status: Yes" headers to the message, and "*****SPAM*****" text string to the beginning of Subject line of each message recognized as spam.

   If you have enabled the Allow personal settings option, then your users will be able to set their spam filters so as to automatically delete junk mail. They will also be able to set up their personal black and white lists of correspondents that will override the server settings, and teach the spam filter on a per-mailbox basis.

6. Adjust the spam filter sensitivity by specifying the desired value in the Hits required for spam box.

   SpamAssassin performs a number of different tests on contents and subject line of each message. As a result, each message scores a number of points. The higher the number, the more likely a message is spam. For example, a message containing the text string "BUY VIAGRA AT LOW PRICE!!!" in Subject line and message body scores 8.3 points. By default, the filter sensitivity is set so that all messages that score 7 or more points are classified as spam.

   - When your users receive lots of spam messages with the current setting, to make filter more sensitive, try setting a lesser value in the Hits required for spam box; for example, 6.
   - When your users are missing e-mails because your spam filter thinks they are junk, try reducing filter sensitivity by setting a higher value in the Hits required for spam box.
   - Testing large messages can slow down the mail server. To reduce the load, you can select the Do not filter if mail size exceeds specified size checkbox and specify the maximum size of the message that the spam filter will test. Recommended mail size limit is 150 - 250 Kbytes, which is usual for mail messages in HTML format with images. The size of the mail is considered critical for filter and server overload when it exceeds 500 Kbytes, which is usual for mail messages containing attachments.
   - To avoid spam filter leaving some mail messages unchecked (this can happen if the amount of incoming mail is very large), limit the number of letters that can be checked simultaneously in the Number of threads that spam filter can create field.
7. Specify how to mark messages recognized as spam.

   At the server level, you cannot set the server-wide spam filter to automatically delete spam: you can do it only on a per-mailbox basis. So, for the server-wide policy, you can choose only marking messages as spam: "X-Spam-Flag: YES" and "X-Spam-Status: Yes" headers are added to the message source by default, and if you want, the spam filter will additionally include a specific text string to the beginning of Subject line. To include a desired combination of symbols to the message subject, type it into the by tag box. If you do not want the spam filter to modify message subject, clear the Modify spam mail subject check box. If required, specify the spam detection alert text in the appropriate field.

8. Define the language characteristics of mail that should always pass the filter by specifying trusted languages and locales.
   - Select the required items from the boxes under Trusted languages and Trusted locales and click Add >>.
   - Letters written in the specified languages and with the defined character sets will not be marked as spam.
9. Once finished with setting up SpamAssassin spam filter, click Up Level to return to the previous screen.

If you wish to adjust spam filtering settings for a specific mailbox, proceed to the Protecting Mailboxes from Spam section.