Configure additional proxy addresses in PowerShell

Configure additional Proxy addresses

$users = Get-Mailbox
forech ($a in $users){$a.emailaddresses.add("smtp:$($.alias)@thenewdomainname")}
$users | %{Set-Mailbox.$_.Identity -Emailaddresses$_.EmailAddresses}

Configure Additional Addresses using a CSV file

Import-CSV "C:addaddresses.csv" | ForEach {Set-Mailbox $_.Mailbox -EmailAddresses @{add$_.NewEmailAddress}}