UNC path cannot access through explorer.exe

Hi all,

I am sharing my document with my teammates, which located in windows 2012 file server, so I attached the file UNC path in an email and distribute to them. But they cannot access the file when they click on the link, the system shown

I am sure my teammates have sufficient NTFS and windows share right to read the file, because we are mapping same network folder. I was checked my teammates has proper right to access the file from "effective permission" on windows server. Also, my teammates can browse "\ad.local\filesrv\pool$\department\" without any problem.

I...