This Exchange Server cmdlet will help you find users with specific SMTP domain address, this is useful when you what to know how many users using a specific domain.
To run the cmdlet, open Exchange shell and type the following cmdlet.
get-recipient -ResultSize unlimited | where {$_.emailaddresses -match "test.local"} | select name,emailaddresses
If you need to expert the list to a text file use this like.
get-recipient -ResultSize unlimited | where {$_.emailaddresses -match "test.local"} | select name,emailaddresses > c:\out.txt
If you need to find just an email address add name@test.local to the line.
get-recipient -ResultSize unlimited | where {$_.emailaddresses -match "test@test.local"} | select name,emailaddresses > c:\out.txt