In the "System Mail Preferences", there is an option to forward mail sent to cpanel... yet there is no explanation on when/why this email would ever be used.
You will also notice on on the same Mail Preferences page, that there are notes about all three other forwards... except the cpanel one.
* root generally gets email about problems on the server, and normal server activity.
* nobody receives bounce message from email sent via cgi scripts if you are not using suexec.
* mailman generally receives only bounce messages from the mailman list software.
I'm just concerned with the cpanel email because it seems to randomly appear in cc lists of my clients email when they hit "reply-all".
Mails sent as a notification when account is created, terminated, suspended, unsuspended, account upgrade/downgrade, disk space warnings etc will be sent as cpanel mails which in turn will be forwarded to your email address. That way you are always notified of any such account updates on your server.