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Attachment file types

Use Attachment file types (AFT) to detect attachments based on their file extensions or file groups.

We recommend that you use the Sophos list. This list includes predefined file types that are selected to help detect commonly controlled attachments accurately.

You can use a custom list if you need to change the predefined file type selections. If you use a custom list, you can filter by file extensions or file groups.

If you filter by file extensions, you can select individual file extensions. You can't select a file group. The rule matches against file extensions, not the file types we detect.

Selecting file extensions from the list doesn't automatically add them to the Include extensions list. To add more file extensions, enter them manually in Include extensions.

Note these rules when adding file extensions manually:

  • Start each file extension with a dot.
  • Separate file extensions with commas.
  • Enter file extensions without spaces between them.
  • Enter up to 1,000 characters.

An error is shown if the entries don't follow the required format.

Example 
.doc,.docx,.pdf,.zip

If you filter by file groups, you can select groups of file types from the list. You can't select individual file extensions. The rule matches against the file types we detect, not extensions.