For example, you can add an entry for firstname.lastname@example.org forwarding to email@example.com. This will cause any mail addressed to firstname.lastname@example.org to be forwarded automatically to the external email address.
This is useful for the "Page Not Found" messages which are automatically generated by the server.
For example, see the linked email address here: http://warez.memebot.com/notfound
You can add wildcard mail forwarding by using a "*" as the from address. This will forward all mail to anyone @ your.site.name to the specified destination. Probably we should add a wildard forward by default.
Note that if no forward is established for any email address on your account, then the sender may see a "bounce" message which contains the following:
554 <email@example.com>: Relay access denied
For technical reasons beyond the scope of this faq, the "bounce" message in such cases does not say "No such user".