We have several users that cannot open a PDF email attachments. We are primarily using Outlook 2010 with Adobe Acrobat Pro DC version 2015.006.30418. Now if that a user takes the file and moves it to their desktop the PDF opens. We have also had in some cased where a user will attach a PDF to an email and for some reason the name of the PDF changes.
As per the issue description mentioned above, pdf email attachments not opening with Adobe Acrobat, is that correct?
Could you try following troubleshooting steps:
1- Reboot the machine if you haven't already and check if that resolves the issue.
2- Launch Acrobat > Edit > Preferences > Trust Manager -> 'Allow opening of non-PDF file attachments with external application' > click OK and try again.
3- If that doesn't work, try disabling protected view by clicking Edit > Preferences > Security(Enhanced) > click Off under protected view > click OK and try again.
Note: Disabling protected view is for troubleshooting purpose only. Enable protected view when troubleshooting is complete.
Keep us posted with the results.