Login to your WebMail using the administrative account.
User Name: firstname.lastname@example.org
Click on the Settings button on the top of the page.
Select, "Mail Aliases & Consolidation" from the left-hand side menu options.
Select, "Mail Aliases".
Click on the, "Add a new mail alias to a domain name" button.
Under the "Mail Alias Name" field, add a " * ".
Now select your domain name from the "Domain" drop-down menu.
After you have inputted everything into the two fields, everything should look like the following: *@domain-name.com
Click on the, "Add Mail Alias" button to create your "catchall" account.
Please keep in mind that ALL e-mail for domain-name.com will be received. Please note that having a "catchall" like this can dramatically increase the amount of SPAM messages you receive, seeing absolutely any e-mail address at yourdomain.com becomes valid and will therefore be vulnerable to dictionary-type spam attacks.