Looking for a mail server program. which can provide Pop3/SMTP for multiple domains. I am looking for a backup solution for my customers if their Exchange servers go down. I am looking for something which is free, host multiple domains, supports aliases for email addresses. Needs to run on windows and hopefully doesnt require any programming to install. I am not looking for the POP3 server which comes with windows 2003 server because as far as I know it does not support aliases for email addresses.