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 = 202.55.55.202
Where,
*
bind = 202.55.55.202: Qmail IP address to bind.
2) Save file
3) Reload xinetd with any one of the following command:
# /etc/init.d/xinetd reload
OR
/etc/init.d/xinetd restart