Some times in cpanel server mail server server IP get blocked due to email spamming, So A question arise in our mind ” How to change Outgoing mail IP in exim ? ” in this case we need to change outgoing IP of mail server.You can use below command for IP change.
Login to your server via root access and open mailips by text editor. Here we are using nano and enter your IP and save it.
nano /etc/mailips
*: your new IP address

Now login to your server by using WHM/cPanel and go to exim configuration manager after that you will see section domain and IPs section select option  Reference /etc/mailips for outgoing SMTP connections and enabled this feature.

Hope this article will help you to change mail server IP.