Hello everyone! My server using CentOS 5.6_64bit and Postfix_2.8.4 for Mail Server. My server have 5 IPs address.
What can I do to use one SMTP user for one IP?

eg:user1[at]smtp1[dot]domain[dot]com ---------> 98.129.12.123
user1[at]smtp1[dot]domain[dot]com------------> 98.129.12.124

Someone can help me?