Each e-mail address is normally associated with a single user's mailbox on your server. In some situations, however, it's beneficial to forward incoming mail to multiple users or to an address on another server. This can be achieved by using mail aliases, which Postfix supports and Webmin makes easy to administer.
Tip
There are a number of aliases which every mail server should define. For instance, mail to the root mailbox should always reach an actual person. If you're running a mail server, you should also define aliases named postmaster and abuse through which people can report mail-related issues. If you wish to read mail sent in reply to automated messages from your MTA, define an alias for mailer-daemon.
More information about common mailbox names may be found in the RFC2142 document at http://tools.ietf.org/html/2142.
Postfix aliases allow you to not only forward mail to other addresses, but also save their content to files or pipe them to other applications...