When opening Microsoft Word attachments in ThunderBird with office 2013 the attachments open in “read only” mode.

Solution:
From ThunderBird:

  1. Open from the “Tools” and select “Options”.
  2. Go to the “Advanced” pane and select the “General” tab.
  3. Click “Config editor” and confirm the security warning.
  4. Search for “browser.helperApps.deleteTempFileOnExit” and if you find it, double click it and set the value to False.
  5. If you don’t find it, right click into the main area, choose “New” > “Boolean”, add “browser.helperApps.deleteTempFileOnExit” as name and choose “False” as value.
  6. Restart ThunderBird

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