Kaspersky Secure Mail Gateway

Configuring Content Filtering

Before configuring Content Filtering in the message processing rule, make sure that Content Filtering is enabled in general protection settings.

To configure Content Filtering in the message processing rule:

1. In the application web interface window, select the Rules section.
2. In the rule table, select the rule for which you want to configure Content Filtering.

   This opens the View rule window.

3. Click Edit.

   Rule settings become editable.

4. In the left pane, select the Content Filtering section.
5. Use the toggle switch to the right of the section title to enable or disable content filtering of messages that match rule criteria.

   By default, Content Filtering of messages is disabled.

6. If at the previous step, you have enabled Content Filtering, configure the following filtering criteria:
   • By message size
     1. If you want to restrict the sending of messages that contain attachments of a certain size, in the If the allowed message size is exceeded group of settings, in the drop-down list, select an action to apply to messages:
        • Skip.
        • Delete message.
        • Reject.

        The Reject action is selected by default.

     2. If you want to automatically place messages containing attached objects of a certain size in Backup based on the scan results, select the Move copy to Backup check box.

        This check box is selected by default.

     3. If you want a tag to be automatically added after the scan to the beginning of the subject of messages that contain attachment objects of a certain size, type the text of the tags in text boxes under the Move copy to Backup check box.

        By default, no tag is assigned.

     4. In the Message size (KB) field, type the maximum size of objects in the range from 0 KB to 1,048,576 KB (1 GB).

        If the value is set to 0 KB, no restrictions apply to the size of objects.

   • By attachment format
     1. If you want to restrict the sending of messages that contain attachments of a particular format, in the If attachment type is detected group of settings, create a list of attachment formats to which the rule must apply. To do so:
        1. Select a list creation method:
           • Attachments that have type from the list below if you want to specify attachment formats that you want to add to the list.

             Content Filtering settings will be applied to messages containing attachments that have specified formats.

           • Attachments that have type NOT from the list below if you want to specify attachment formats that you want to exclude from the list.

             Content Filtering settings will not be applied to messages containing attachments that have specified formats.

        2. Click Edit to open the File formats window.
        3. Select check boxes next to attachment formats that you want to add to the list or exclude from the list:
           • Archives (e.g., ZIP; RAR; TGZ)
           • Databases (e.g., ACCDB; ACCDC; MDB)
           • Executable files (e.g., EXE; DLL; OCX)
           • Graphic files (e.g., JPG; BMP; WMF)
           • Multimedia files (e.g., AVI; WMV; MP3)
           • Document files (e.g., DOC; XLS; PDF; PPT)
           • Other files (e.g., TXT; CHM; HTM)
        4. In the lower right corner, click OK.
     2. In the In case of detection drop-down list, select the action that will be applied to messages:
        • Skip.
        • Delete message.
        • Delete attachment.
        • Reject.

        The Reject action is selected by default.

     3. If you want to automatically place messages containing attachments of the specified formats in Backup based on the scan results, select the Move copy to Backup check box.

        This check box is selected by default.

     4. If you want a tag to be added after the scan to the beginning of the subject of messages that contain attachment objects of a certain format, type the text of the tags in text boxes under the Move copy to Backup check box.

        By default, no tag is assigned.

   • By attachment name.
     1. If you want to restrict the sending of messages that contain attachments with certain names, under Attachment name, in the Names of attachments field, enter the names of such attachments.

        You can use masks and regular expressions in an attachment name. Names can contain any characters. Use semicolons ";" to separate the names.

        Masks and regular expressions are not case-insensitive.

        For example, you can enter the *.exe name mask to restrict transmission of messages that include attachments with the EXE extension.

        To restrict the sending of messages that contain executable files of widespread formats, you can use the following regular expression:

        re:.*\.(scr|cpl|com|bat|cmd|vbs|pif|lnk|url|exe|bvs|spl|dll)

     2. In the In case of detection drop-down list, select the action that you want to apply to messages:
        • Skip.
        • Delete message.
        • Delete attachment.
        • Reject.

        The Reject action is selected by default.

     3. If you want to automatically place messages containing attachments with the specified names in Backup based on the scan results, select the Move copy to Backup check box.

        This check box is selected by default.

     4. If you want a tag to be automatically added after the scan to the beginning of the subject of messages that contain attachment objects of a certain format, type the text of the tags in text boxes under the Move copy to Backup check box.

        By default, no tag is assigned.

7. If you want to scan for forbidden formats or names of files within compound objects (including archives), select the Scan compound objects check box.

   If you enable scanning compound objects, the Scan file formats and names in archive check box is selected automatically because archives are a subset of compound objects.

8. If at the previous step, you did not enable scanning compound objects and want to scan for forbidden formats or filenames only in archives, select the Scan file formats and names in archive check box.
9. Click Save.

Content Filtering is configured. The specified settings are applied to messages that match the rule criteria.

To ensure the configured settings are applied during the operation of Kaspersky Secure Mail Gateway, make sure to enable Content Filtering for the rule and to enable the configured rule.