Unlimited E-Mail Aliases
E-mail aliases allow you to setup as many e-mail addresses as you would like for any domain. E-mail aliases are just "aliases" of a POP3 account within your domain. Aliases can only be setup to direct something@yourdomain.com (Alias) to somethingelse@yourdomain.com (POP3 account). This means that they will not be able to point to another domain. You can have multiple aliases pointing to the same POP3 account.
An Example: Say Greg is the manager of your business. He needs all e-mail to Manager@yourdomain.com, CEO@yourdomain.com, to be directed to the POP3 account of his, which is going to be the Greg@yourdomain.com e-mail address. Manager@yourdomain.com and CEO@yourdomain.com would both be e-mail aliases of greg@yourdomain.com and all mail sent to any of these three e-mail addresses would be directed to the greg@yourdomain.com POP3 account. Earthfirst does not restrict the amount of aliases that you setup.