I have cPanel/WHM CentOS based server. Please tell me, how do I configure a backup server where all the copies of Incoming and Outgoing emails will be saved ?
Cpanel use EXIM as mail client so first you need to check if the EXIM is compatible with the configuration. But if you are looking for a solution like Fail over then it will be suggested to use Postfix and Haproxy which works like a charm.