What all should be done to support virtual hosting.
I want to use the same mail server instalation to handle mail traffic for more than 1 domain.
(i.e.) The MX record of both ABC.com and XYZ.com will be pointed to the same mail server IP.

1. There can be 2 different users named "john" in ABC.com and XYZ.com
john@abc.com and john@xyz.com.

2. Each domain should have a postmaster mail id.
postmaster@abc.com and postmaster@xyz.com

3. Is there anyting else I should keep in mind.

Please help me with your ideas. I need support for both POP and SMTP.