Sometimes you will need to find users by specific domain. Here is short PowerShell cmdlet which you can use:
Note:
I will use new Get-EXOMailbox cmdlet, and Exchange Management Module V2 is mandatory for that.
Get-EXOMailbox -ResultSize Unlimited -Filter {EmailAddresses -like "*@domain.com"} | Select DisplayName
Replace @domain.com with your desired domain.
Additionally you can export the result with Export-CSV cmdlet.
Example:
Export-CSV -path $env:USERPROFILE\Desktop\output.csv