Problem
When the Outlook Temp folder if full, PDF attachments in Outlook fail to open and throw up an error “It is not possible to create a file, verify permissions”
Solution
Outlook saves PDF attachments in the Outlook temp folder which has a maximum file size. Once in is full Outlook PDF attachments will not open
To delete the files Press Windows-E to launch File Explorer
Paste in the empty part of the browser address bar
C:\Users\%username%\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook\
Enter. Open the randomly name folder (there may be more than one) and you will see all the temporary files.
Select All Delete.