qmail is a mail transfer agent that runs on Linux and Unixish oses. It is more secure replacement for the popular Sendmail program. Yes, it is possible to bind Qmail to specific IP. Here is what I did. Please note that I am running light weight QMAIL server from xinetd service.
1) Open your /etc/xinetd.d/smtp file and add bind=IP line:
# vi /etc/xinetd.d/smtp
Append/add following line to it:
bind = 220.127.116.11
bind = 18.104.22.168: Qmail IP address to bind.
2) Save file
3) Reload xinetd with any one of the following command:
# /etc/init.d/xinetd reload