Windows 2003 with POP3 & SMTP Services

Install POP3 & SMTP services from your CD first.

Open POP3 Service manager, [Your machine name]->New->Domain...
enter a name for your domain, add mainboxes in your domain
then change your service config like this:
server port: 110
logging level: minimum
DO NOT select "Require Secure Password Authentication (SPA) for all client connections"

open your Internet Information Services (IIS) Manager
change your smtp sercice config like this:
in Access->Access control, select All items
in Delivery->Outbound Security, select "Anonymous access"
in Security, add the usergroup names "POP3 Users"

then, everything will be OK