Creating lists to detect file attachment types

book

Article ID: 179044

calendar_today

Updated On:

Products

Messaging Gateway

Issue/Introduction

 

Resolution

Use attachment lists in content filtering policy conditions to detect and act on email attachment file types. For example, you can assign an attachment list that detects messages with .exe file attachments as a condition in a content filtering policy. You can then specify what action you want Symantec Messaging Gateway to take if messages with an .exe file attachment are detected.

Symantec Messaging Gateway provides default attachment lists that you can use to create your attachment list. All of the attachments lists (default and custom) appear in the Conditions section on the Email Content Filtering Policy page. So you can conveniently select the attachment list that you want to use as a condition when you configure a content filtering policy.

When you create an attachment list, you can use any combination of true file classes, true file types, and common file extensions and MIME-types.

Note:

MIME-type and file extension-based attachment lists are ineffective for stripping the attachments that are not described in the MIME header (for example, in the case of some forwarded messages). To ensure that you strip all instances of an attachment file type, configure your attachment lists to use true file type whenever possible.

To create an attachment list, you must have Full Administration rights or rights to modify policies.

See About attachment lists.

See Editing attachment lists.

To create lists to detect file attachment types

  1. In the Control Center, click Content > Resources > Attachment Lists.

  2. Click Add.

  3. In the Attachment list name box, type a name for the attachment list.

  4. Under Add Attachment Types, do any of the following tasks:

    To add a true file class to your attachment list

    Do all of the following tasks:

    • Above the File classes list, click the radio button beside If the.

    • Click the attachment type drop-down list and select True file class.

    • In the File classes list, select the class or classes that you want to add to your attachment list.

      You can press and hold Ctrl to select multiple, non-consecutive items. You can also press and hold Shift to select consecutive blocks of items.

    When you select a true file class, you add every true file type that is within that class to your attachment list. You cannot add or remove any file types.

    To add a true file type to your attachment list

    Do all of the following tasks:

    • Above the File classes list, click the radio button beside If the.

    • Click the attachment type drop-down list and select True file type.

      True file type is the default option.

    • In the File classes list, select the true file class that contains the true file types that you want to add to your attachment list.

      You can press and hold Ctrl to select multiple, non-consecutive items. You can also press and hold Shift to select consecutive blocks of items.

      See Default attachment lists.

    • In the File types box, select the true file types that you want to add to your attachment list.

    To add a file extension based on file names, extensions, or MIME types

    Do all of the following tasks:

    • To add your own extension, under the File classes list, click the radio button beside If the.

    • Click the Extension drop-down list and select one of the following options:

      • File name

      • Extension

        This value is the default.

      • MIME-type

    • Click the is drop-down list and select one of the following options:

      • contains

      • begins with

      • ends with

      • is

        This value is the default.

    • In the adjacent text box, type only one file name, extension, or MIME type.

      Type the MIME type completely, such as image or image/gif.

  5. Click Add to add the attachment type to the attachment list.

  6. Repeat steps 4 and 5 to add more attachment types to the attachment list.

  7. Click Save.