Change CPanel Outgoing Email IP

Official documentation :
https://documentation.cpanel.net/display/CKB/How+to+Configure+the+Exim+Outgoing+IP+Address

The /etc/mailips file controls the IP address from which each domain sends mail.

To change specific domain outgoing email IP simply

[root@cpanel ~]# cat /etc/mailips 
*: 111.222.222.112
domain.com: 111.222.222.112
domain.net: 111.222.222.113
domain.my: 111.222.222.113
domain.org: 111.222.222.114
vi /etc/mailips
Restart the exim service
service exim restart