The 10 rows are reserved for specific mail forwarding options. For example, if your default forwarding address is at AOL, but you want sales@yourdomain.com to forward to an address at Compuserve, your mail forwarding options would look like so:

Procmail is available to allow ultimate control of email forwarding and processing if you end up using all ten rows. Contact support@internet-sites.com for more information.

*** Important ***
You do NOT need to list the usernames that you wish to forward to the to the default address in the 10 rows. This is actually redundant.