This script will show you how to check the proxy addresses of a list of users:
This script will run on Windows Server 2008 R2 and above with AD tools Installed.
Before you start create a text file called users and add the users samaccountname to it like the example below:
User1 User2
#CHECK_PROXY import-module activedirectory get-content C:\scripts\users.txt | Get-ADUser -Properties proxyaddresses | select proxyaddresses