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Barracuda CloudGen Firewall

This Firmware Version Is End-Of-Support

Documentation for this product is no longer updated. Please see https://campus.barracuda.com/doc/71862301/ for further information on our EoS policy.

How to Improve Spam Filtering

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Because spam filtering is based on email classifications according to specific iterative attributes, SpamAssassin may not be able to correctly detect all spam and may even incorrectly tag ham emails as spam. To improve the filtering mechanism, you can configure mail servers to provide misclassified emails to SpamAssassin in the following mailboxes: 

  • SPAM – Contains spam that was delivered and not tagged.
  • HAM – Contains mail that was incorrectly tagged as spam.
  • FORGET – Contains mail that should not be tagged as spam or ham. 

SpamAssassin regularly collects and processes the mail from these training mailboxes to improve its filter mechanisms.

Before configuring the training settings on the Barracuda NG Firewall, set up the training environment. Create a separate mail account for testing. If you use a real mail account, it will be classified as one that sends spam. The training mailboxes must be configured on the mail server and not on the Barracuda NG Firewall. For more information, see How to Set Up a Training Environment. For the correct path to these mailboxes, please consult your mail server administrator.

After setting up the training environment, complete the followings steps to configure the training settings on the Barracuda NG Firewall:

  1. Go to CONFIGURATION > Configuration Tree > Box > Virtual Servers > your virtual server > Assigned Services > SPAM-Filter > SPAM Filter Settings.
  2. Click Lock.
  3. Next to TRAININGS OPTION, click Set or Edit.
  4. Select the Enable Training check box and configure the following settings:

    SettingDescription

    Mailserver (IMAP)

    The IP address and name of the external mail server.

    The mail server must be capable of IMAP.

    Account

    The user name and account name for the external mail server.

    Password

    The password for the mail account.

    Only use English characters and digits. Avoid blanks.

    Mailbox SPAM

    The path to the mailbox that collects spam which was delivered and not tagged as such. Depending on the directory structure, it may be necessary to enter a name space (for example, ~/mail/SPAM). By default, if the folder name is simply specified as SPAM, the user’s home directory (/home/) is queried.

    Mailbox HAM

    The path to the mailbox that collects ham mail which was incorrectly tagged as spam. Depending on the directory structure, it may be necessary to enter a name space (for example, ~/mail/HAM). By default, if the folder name is simply specified as HAM, the user’s home directory (/home/) is queried.

    Mailbox FORGET

    The path to the mailbox that collects mail which should not be classified as spam or ham. Depending on the directory structure, it may be necessary to enter a name space (for example, ~/mail/FORGET). By default, if the folder name is simply specified as FORGET, the user’s home directory (/home/) is queried.

    Keep Mails In Mailbox

    To keep emails in the mailboxes for other servers to learn from (especially when using multiple spam filter servers), select this check box.

    The contents of the mailboxes are only learned once. When you add new emails to a bundle of emails in a mailbox that have already been processed, only the new emails are learned.

    Time (h) |
    Time (min)

    The time of day when the spam filter collects and processes mail from the SPAM, HAM, and FORGET mailboxes to improve its filtering mechanism. For example, if you want to set the time at 4:30 am, enter the following settings:

    • Time (h): 4
    • Time (min): 30
  5. Click OK.
  6. Click Send Changes and Activate.
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