Adobe Reader disable protected mode. this also works for adobe reader enable protected mode
However if you know the attachments and links aren’t malicious and from a trusted source you can disable this and use the PDF document full-scale.
Adobe Reader disable protected mode
- Open Adobe Reader / Acrobat
- press CRTL + K at the same time
- Follow the screenshot:
- Checking that box will enable safe mode reading.
For foxit reader go here.