Mail Relay from specific IP

==== Required information ====
- iRedMail version: 0.8.4
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: CentOS 6.3 64 bit

We are implementing iRedMail which requires to relay emails sent from  SAP ERP servers having public IP. From whatever, I have
read, one requires to make changes to the my.cnf file in PostFix and update the required IP's to the mynetworks parameter like:

mynetworks = 127.0.0.0/8, a.b.c.d/e

Is this all that is required or is there something more to be done.

BR

Dr Yashodhan Joshi
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