E-mail forwarders and aliases are e-mail addresses such as billing@yourdomain.com which do not have a username/password as a "POP" account would. Instead, you would set up billing@yourdomain.com to forward to a real POP account such as customerservice@yourdomain.com. The only real distinction between an alias and a forward, is than an alias will likely forward to another existing account at the same domain, whereas a forward might be sent to another e-mail account with an ISP: such as cs@yourdomain.com being forwarded to cs@gte.net or similar.