One of the most powerfull feature of Exchange logs is the possibility to audit for example all emails send from the source domain: every day and send a mail to some user, this is one sample scrit that colects information and sends a mail:

$file= "c:\prova.csv" 
$mailboxdata= Get-MessageTrackingLog -Start "10/14/2013 00:00:00"| Where-Object {$_.sender -like "*"} | Select-Object eventid,sender,timestamp,@{Name="Recipients";Expression={$_.recipients}},@{Name="RecipientStatus";Expression={$_.recipientstatus}},messagesubject $mailboxdata | export-csv "$file" 
$smtpServer = "" 
$att = new-object Net.Mail.Attachment($file) 
$msg = new-object Net.Mail.MailMessage 
$smtp = new-object Net.Mail.SmtpClient($smtpServer) 
$msg.From = "" 
$msg.Subject = "Emails Summary" 
$msg.Body = "Attached is the email server mailbox report"