Workaround for S/MIME encrypted attachments in macOS Sierra

Sep 8, 2017 09:58 · 103 words · 1 minute read

The version of Apple Mail distributed with macOS Sierra (released in September 2016) introduced a bug that prevents S/MIME-encrypted attachments from being opened or downloaded in Mail. The following steps describe a workaround to access attachments.

  1. Select the email whose attachment you wish to access.
  2. Select the email. Either in the left list of emails or – for threaded conversations in the left message area.
  3. Choose File > Save as to save the email as Raw Message Source
  4. Locate the saved email with Finder and double-click to open.
  5. You can now save your attachment.