Send e-mail through Exim using different IP

We upgraded a server at our NOC a couple of weeks ago and we inherited an IP using by a hosting company that apparently allowed spamming on their servers. Unfortunately, the IP is somehow "banned" by hotmail and our customers are having trouble sending e-mail to hotmail. Most doesn't get there at all and some gets sent to the junk e-mail.

We got a new subnet yesterday and what we intend to do is either:

1) Configure exim to use a different IP (on the new subnet) to send out e-mail. How can this be done? How can it be setup permanently without Cpanel updates wiping it out?

Lets asume we have:

Main server IP: 1.2.3.4
Hostname: machine1.mydomain.com

E-mail currently gets sent from 1.2.3.4 with a HELO of machine1.mydomain.com. As the reverse PTR matches, no worries. However, 1.2.3.4 is banned by hotmail, so e-mail troubles.

We would like to send from 1.2.4.5 with a HELO of exim.mydomain.com. We would set up the PTR of 1.2.4.5 to match the HELO and everything should be transparent. The IP should not be banned by hotmail so problem solved.

How can the IP and HELO be modified in exim.conf? Can it be modified in WHM so that the change is permanent?

2) In case point 1 is too difficult or it cant be made permanent, how can we change the main IP of the server to the new IP on the new subnet? We have the support of our NOC to relicense Cpanel to the new IP if necessary. I looked all over the net last night and there are no clear indications on how to change the eth0 to match the new IP.

Your help is greatly appreciated.

Many thanks

AAG

 

All the additional IPs were entered in WHM (they are eth0:1, eth0:2, etc).

Changing the main Virtual Shared IP doesn't make exim to send mail through that IP, it will continue sending through the server's main IP (eth0:0).

Can anyone at Cpanel chip in on how to modify exim to send out through a different address?