If you want to view all user's email addresses, this information is held in AD under proxyAddresses.

This script will allow you to export proxyAddresses with their Name, UserPrincipalName, proxyAddresses and mail fields. This will allow you to view all the assigned email addresses for the user easily. The line with SMTP is their primary; all the other emails with smtp are secondary.

The searchbase you can either remove or place in the OU you wish to export the information for. If you don't know how to find it, see our article about OU path.

			
				Get-ADUser -Filter "enabled -eq 'true'" -SearchBase "OU=Personel,DC=mydomain,DC=com" -Properties proxyAddresses, mail | select Name, UserPrincipalName, proxyAddresses, mail | Export-Csv -Path "c:\temp\emails.csv" -NoTypeInformation