IP Rotation with Exim

1. vi /etc/exim.conf
2. Search for the line under remote_smtp : interface =

3. Replace this line with interface = xxx.xxx.x.1${eval:${substr{-2}{1}{$tod_zulu}}%9+1}

4. If your server is having ip’s from xxx.xxx.x.11 to xxx.xxx.x.20 , you can use above line.
+1 is is the starting ip ie xxx.xxx.x.1′1′ and %9 is the increment value ie 11(xxx.xxx.x.11) to how much. Here it is 20 (xxx.xxx.x.20)

example : interface = xx.xx.xxx.${eval:${substr{-2}{1}{$tod_zulu}}%15+96}
This will rotate IP from .96 to .111