$list = Get-MailboxPermission -Identity info@contoso.com | ?{$_.User -like "Contoso\*" -and $_.IsInherited -eq $false}; $ergUser = @(); foreach($a in $list){$b = Get-Mailbox -Identity ($a.User.SubString($a.User.IndexOf("\"))); $ergUser += $b;}; $ergUser

oder etwas hübscher formatiert:

$list = Get-MailboxPermission -Identity info@contoso.com | ?{$_.User -like "Contoso\*" -and $_.IsInherited -eq $false}; 
$ergUser = @(); 
foreach($a in $list)
{
  $b = Get-Mailbox -Identity ($a.User.SubString($a.User.IndexOf("\"))); 
  $ergUser += $b;
}; 
$ergUser