DCI / Gateway

What is the issue?

Legitimate email with the MIME type application/octet-stream is being blocked as "Banned".

What causes this issue?

The application/octet-stream is a MIME type that is generically used for attaching several types of files to messages, including:

  1. Images
  2. Executables (including viruses)
  3. .doc and .xls files (including those with viruses)
  4. .docx and .xlsx files (that are legitimate)
  5. .pdf files (that are legitimate)
  6. .ZIP and other archive
  7. others

Given the generic nature of this MIME type, it should never be used either to block or allow in Content Filtering > Attachment > Mime Type Filters.

What is the solution?

  1. Go to Content Filtering > Attachments > Mime Type Filters. 

  2. If "application/octet-stream" is listed in the Mime Type column, delete the entry by clicking the delete X icon in the Options column.

  3. Click Apply at the bottom of the page to force the setting to take effect immediately.